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32 results

drm_fb_helper.c

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  • drm_fb_helper.c 68.59 KiB
    /*
     * Copyright (c) 2006-2009 Red Hat Inc.
     * Copyright (c) 2006-2008 Intel Corporation
     * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
     *
     * DRM framebuffer helper functions
     *
     * Permission to use, copy, modify, distribute, and sell this software and its
     * documentation for any purpose is hereby granted without fee, provided that
     * the above copyright notice appear in all copies and that both that copyright
     * notice and this permission notice appear in supporting documentation, and
     * that the name of the copyright holders not be used in advertising or
     * publicity pertaining to distribution of the software without specific,
     * written prior permission.  The copyright holders make no representations
     * about the suitability of this software for any purpose.  It is provided "as
     * is" without express or implied warranty.
     *
     * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
     * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
     * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
     * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
     * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
     * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
     * OF THIS SOFTWARE.
     *
     * Authors:
     *      Dave Airlie <airlied@linux.ie>
     *      Jesse Barnes <jesse.barnes@intel.com>
     */
    #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
    
    #include <linux/console.h>
    #include <linux/dma-buf.h>
    #include <linux/kernel.h>
    #include <linux/module.h>
    #include <linux/slab.h>
    #include <linux/sysrq.h>
    #include <linux/vmalloc.h>
    
    #include <drm/drm_atomic.h>
    #include <drm/drm_crtc.h>
    #include <drm/drm_crtc_helper.h>
    #include <drm/drm_drv.h>
    #include <drm/drm_fb_helper.h>
    #include <drm/drm_fourcc.h>
    #include <drm/drm_print.h>
    #include <drm/drm_vblank.h>
    
    #include "drm_internal.h"
    
    static bool drm_fbdev_emulation = true;
    module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600);
    MODULE_PARM_DESC(fbdev_emulation,
    		 "Enable legacy fbdev emulation [default=true]");
    
    static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC;
    module_param(drm_fbdev_overalloc, int, 0444);
    MODULE_PARM_DESC(drm_fbdev_overalloc,
    		 "Overallocation of the fbdev buffer (%) [default="
    		 __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]");
    
    /*
     * In order to keep user-space compatibility, we want in certain use-cases
     * to keep leaking the fbdev physical address to the user-space program
     * handling the fbdev buffer.
     * This is a bad habit essentially kept into closed source opengl driver
     * that should really be moved into open-source upstream projects instead
     * of using legacy physical addresses in user space to communicate with
     * other out-of-tree kernel modules.
     *
     * This module_param *should* be removed as soon as possible and be
     * considered as a broken and legacy behaviour from a modern fbdev device.
     */
    #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
    static bool drm_leak_fbdev_smem = false;
    module_param_unsafe(drm_leak_fbdev_smem, bool, 0600);
    MODULE_PARM_DESC(drm_leak_fbdev_smem,
    		 "Allow unsafe leaking fbdev physical smem address [default=false]");
    #endif
    
    static LIST_HEAD(kernel_fb_helper_list);
    static DEFINE_MUTEX(kernel_fb_helper_lock);
    
    /**
     * DOC: fbdev helpers
     *
     * The fb helper functions are useful to provide an fbdev on top of a drm kernel
     * mode setting driver. They can be used mostly independently from the crtc
     * helper functions used by many drivers to implement the kernel mode setting
     * interfaces.
     *
     * Drivers that support a dumb buffer with a virtual address and mmap support,
     * should try out the generic fbdev emulation using drm_fbdev_generic_setup().
     *
     * Setup fbdev emulation by calling drm_fb_helper_fbdev_setup() and tear it
     * down by calling drm_fb_helper_fbdev_teardown().
     *
     * At runtime drivers should restore the fbdev console by using
     * drm_fb_helper_lastclose() as their &drm_driver.lastclose callback.
     * They should also notify the fb helper code from updates to the output
     * configuration by using drm_fb_helper_output_poll_changed() as their
     * &drm_mode_config_funcs.output_poll_changed callback.
     *
     * For suspend/resume consider using drm_mode_config_helper_suspend() and
     * drm_mode_config_helper_resume() which takes care of fbdev as well.
     *
     * All other functions exported by the fb helper library can be used to
     * implement the fbdev driver interface by the driver.
     *
     * It is possible, though perhaps somewhat tricky, to implement race-free
     * hotplug detection using the fbdev helpers. The drm_fb_helper_prepare()
     * helper must be called first to initialize the minimum required to make
     * hotplug detection work. Drivers also need to make sure to properly set up
     * the &drm_mode_config.funcs member. After calling drm_kms_helper_poll_init()
     * it is safe to enable interrupts and start processing hotplug events. At the
     * same time, drivers should initialize all modeset objects such as CRTCs,
     * encoders and connectors. To finish up the fbdev helper initialization, the
     * drm_fb_helper_init() function is called. To probe for all attached displays
     * and set up an initial configuration using the detected hardware, drivers
     * should call drm_fb_helper_initial_config().
     *
     * If &drm_framebuffer_funcs.dirty is set, the
     * drm_fb_helper_{cfb,sys}_{write,fillrect,copyarea,imageblit} functions will
     * accumulate changes and schedule &drm_fb_helper.dirty_work to run right
     * away. This worker then calls the dirty() function ensuring that it will
     * always run in process context since the fb_*() function could be running in
     * atomic context. If drm_fb_helper_deferred_io() is used as the deferred_io
     * callback it will also schedule dirty_work with the damage collected from the
     * mmap page writes. Drivers can use drm_fb_helper_defio_init() to setup
     * deferred I/O (coupled with drm_fb_helper_fbdev_teardown()).
     */
    
    static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
    {
    	uint16_t *r_base, *g_base, *b_base;
    
    	if (crtc->funcs->gamma_set == NULL)
    		return;
    
    	r_base = crtc->gamma_store;
    	g_base = r_base + crtc->gamma_size;
    	b_base = g_base + crtc->gamma_size;
    
    	crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
    			       crtc->gamma_size, NULL);
    }
    
    /**
     * drm_fb_helper_debug_enter - implementation for &fb_ops.fb_debug_enter
     * @info: fbdev registered by the helper
     */
    int drm_fb_helper_debug_enter(struct fb_info *info)
    {
    	struct drm_fb_helper *helper = info->par;
    	const struct drm_crtc_helper_funcs *funcs;
    	struct drm_mode_set *mode_set;
    
    	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
    		mutex_lock(&helper->client.modeset_mutex);
    		drm_client_for_each_modeset(mode_set, &helper->client) {
    			if (!mode_set->crtc->enabled)
    				continue;
    
    			funcs =	mode_set->crtc->helper_private;
    			if (funcs->mode_set_base_atomic == NULL)
    				continue;
    
    			if (drm_drv_uses_atomic_modeset(mode_set->crtc->dev))
    				continue;
    
    			funcs->mode_set_base_atomic(mode_set->crtc,
    						    mode_set->fb,
    						    mode_set->x,
    						    mode_set->y,
    						    ENTER_ATOMIC_MODE_SET);
    		}
    		mutex_unlock(&helper->client.modeset_mutex);
    	}
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_debug_enter);
    
    /**
     * drm_fb_helper_debug_leave - implementation for &fb_ops.fb_debug_leave
     * @info: fbdev registered by the helper
     */
    int drm_fb_helper_debug_leave(struct fb_info *info)
    {
    	struct drm_fb_helper *helper = info->par;
    	struct drm_client_dev *client = &helper->client;
    	struct drm_crtc *crtc;
    	const struct drm_crtc_helper_funcs *funcs;
    	struct drm_mode_set *mode_set;
    	struct drm_framebuffer *fb;
    
    	mutex_lock(&client->modeset_mutex);
    	drm_client_for_each_modeset(mode_set, client) {
    		crtc = mode_set->crtc;
    		if (drm_drv_uses_atomic_modeset(crtc->dev))
    			continue;
    
    		funcs = crtc->helper_private;
    		fb = crtc->primary->fb;
    
    		if (!crtc->enabled)
    			continue;
    
    		if (!fb) {
    			DRM_ERROR("no fb to restore??\n");
    			continue;
    		}
    
    		if (funcs->mode_set_base_atomic == NULL)
    			continue;
    
    		drm_fb_helper_restore_lut_atomic(mode_set->crtc);
    		funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
    					    crtc->y, LEAVE_ATOMIC_MODE_SET);
    	}
    	mutex_unlock(&client->modeset_mutex);
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_debug_leave);
    
    /**
     * drm_fb_helper_restore_fbdev_mode_unlocked - restore fbdev configuration
     * @fb_helper: driver-allocated fbdev helper, can be NULL
     *
     * This should be called from driver's drm &drm_driver.lastclose callback
     * when implementing an fbcon on top of kms using this helper. This ensures that
     * the user isn't greeted with a black screen when e.g. X dies.
     *
     * RETURNS:
     * Zero if everything went ok, negative error code otherwise.
     */
    int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper)
    {
    	bool do_delayed;
    	int ret;
    
    	if (!drm_fbdev_emulation || !fb_helper)
    		return -ENODEV;
    
    	if (READ_ONCE(fb_helper->deferred_setup))
    		return 0;
    
    	mutex_lock(&fb_helper->lock);
    	/*
    	 * TODO:
    	 * We should bail out here if there is a master by dropping _force.
    	 * Currently these igt tests fail if we do that:
    	 * - kms_fbcon_fbt@psr
    	 * - kms_fbcon_fbt@psr-suspend
    	 *
    	 * So first these tests need to be fixed so they drop master or don't
    	 * have an fd open.
    	 */
    	ret = drm_client_modeset_commit_force(&fb_helper->client);
    
    	do_delayed = fb_helper->delayed_hotplug;
    	if (do_delayed)
    		fb_helper->delayed_hotplug = false;
    	mutex_unlock(&fb_helper->lock);
    
    	if (do_delayed)
    		drm_fb_helper_hotplug_event(fb_helper);
    
    	return ret;
    }
    EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode_unlocked);
    
    #ifdef CONFIG_MAGIC_SYSRQ
    /*
     * restore fbcon display for all kms driver's using this helper, used for sysrq
     * and panic handling.
     */
    static bool drm_fb_helper_force_kernel_mode(void)
    {
    	bool ret, error = false;
    	struct drm_fb_helper *helper;
    
    	if (list_empty(&kernel_fb_helper_list))
    		return false;
    
    	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
    		struct drm_device *dev = helper->dev;
    
    		if (dev->switch_power_state == DRM_SWITCH_POWER_OFF)
    			continue;
    
    		mutex_lock(&helper->lock);
    		ret = drm_client_modeset_commit_force(&helper->client);
    		if (ret)
    			error = true;
    		mutex_unlock(&helper->lock);
    	}
    	return error;
    }
    
    static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
    {
    	bool ret;
    
    	ret = drm_fb_helper_force_kernel_mode();
    	if (ret == true)
    		DRM_ERROR("Failed to restore crtc configuration\n");
    }
    static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);
    
    static void drm_fb_helper_sysrq(int dummy1)
    {
    	schedule_work(&drm_fb_helper_restore_work);
    }
    
    static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = {
    	.handler = drm_fb_helper_sysrq,
    	.help_msg = "force-fb(V)",
    	.action_msg = "Restore framebuffer console",
    };
    #else
    static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { };
    #endif
    
    static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    
    	mutex_lock(&fb_helper->lock);
    	drm_client_modeset_dpms(&fb_helper->client, dpms_mode);
    	mutex_unlock(&fb_helper->lock);
    }
    
    /**
     * drm_fb_helper_blank - implementation for &fb_ops.fb_blank
     * @blank: desired blanking state
     * @info: fbdev registered by the helper
     */
    int drm_fb_helper_blank(int blank, struct fb_info *info)
    {
    	if (oops_in_progress)
    		return -EBUSY;
    
    	switch (blank) {
    	/* Display: On; HSync: On, VSync: On */
    	case FB_BLANK_UNBLANK:
    		drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON);
    		break;
    	/* Display: Off; HSync: On, VSync: On */
    	case FB_BLANK_NORMAL:
    		drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
    		break;
    	/* Display: Off; HSync: Off, VSync: On */
    	case FB_BLANK_HSYNC_SUSPEND:
    		drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
    		break;
    	/* Display: Off; HSync: On, VSync: Off */
    	case FB_BLANK_VSYNC_SUSPEND:
    		drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND);
    		break;
    	/* Display: Off; HSync: Off, VSync: Off */
    	case FB_BLANK_POWERDOWN:
    		drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
    		break;
    	}
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_blank);
    
    static void drm_fb_helper_resume_worker(struct work_struct *work)
    {
    	struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
    						    resume_work);
    
    	console_lock();
    	fb_set_suspend(helper->fbdev, 0);
    	console_unlock();
    }
    
    static void drm_fb_helper_dirty_blit_real(struct drm_fb_helper *fb_helper,
    					  struct drm_clip_rect *clip)
    {
    	struct drm_framebuffer *fb = fb_helper->fb;
    	unsigned int cpp = fb->format->cpp[0];
    	size_t offset = clip->y1 * fb->pitches[0] + clip->x1 * cpp;
    	void *src = fb_helper->fbdev->screen_buffer + offset;
    	void *dst = fb_helper->buffer->vaddr + offset;
    	size_t len = (clip->x2 - clip->x1) * cpp;
    	unsigned int y;
    
    	for (y = clip->y1; y < clip->y2; y++) {
    		memcpy(dst, src, len);
    		src += fb->pitches[0];
    		dst += fb->pitches[0];
    	}
    }
    
    static void drm_fb_helper_dirty_work(struct work_struct *work)
    {
    	struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
    						    dirty_work);
    	struct drm_clip_rect *clip = &helper->dirty_clip;
    	struct drm_clip_rect clip_copy;
    	unsigned long flags;
    	void *vaddr;
    
    	spin_lock_irqsave(&helper->dirty_lock, flags);
    	clip_copy = *clip;
    	clip->x1 = clip->y1 = ~0;
    	clip->x2 = clip->y2 = 0;
    	spin_unlock_irqrestore(&helper->dirty_lock, flags);
    
    	/* call dirty callback only when it has been really touched */
    	if (clip_copy.x1 < clip_copy.x2 && clip_copy.y1 < clip_copy.y2) {
    
    		/* Generic fbdev uses a shadow buffer */
    		if (helper->buffer) {
    			vaddr = drm_client_buffer_vmap(helper->buffer);
    			if (IS_ERR(vaddr))
    				return;
    			drm_fb_helper_dirty_blit_real(helper, &clip_copy);
    		}
    		if (helper->fb->funcs->dirty)
    			helper->fb->funcs->dirty(helper->fb, NULL, 0, 0,
    						 &clip_copy, 1);
    
    		if (helper->buffer)
    			drm_client_buffer_vunmap(helper->buffer);
    	}
    }
    
    /**
     * drm_fb_helper_prepare - setup a drm_fb_helper structure
     * @dev: DRM device
     * @helper: driver-allocated fbdev helper structure to set up
     * @funcs: pointer to structure of functions associate with this helper
     *
     * Sets up the bare minimum to make the framebuffer helper usable. This is
     * useful to implement race-free initialization of the polling helpers.
     */
    void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
    			   const struct drm_fb_helper_funcs *funcs)
    {
    	INIT_LIST_HEAD(&helper->kernel_fb_list);
    	spin_lock_init(&helper->dirty_lock);
    	INIT_WORK(&helper->resume_work, drm_fb_helper_resume_worker);
    	INIT_WORK(&helper->dirty_work, drm_fb_helper_dirty_work);
    	helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
    	mutex_init(&helper->lock);
    	helper->funcs = funcs;
    	helper->dev = dev;
    }
    EXPORT_SYMBOL(drm_fb_helper_prepare);
    
    /**
     * drm_fb_helper_init - initialize a &struct drm_fb_helper
     * @dev: drm device
     * @fb_helper: driver-allocated fbdev helper structure to initialize
     * @max_conn_count: max connector count (not used)
     *
     * This allocates the structures for the fbdev helper with the given limits.
     * Note that this won't yet touch the hardware (through the driver interfaces)
     * nor register the fbdev. This is only done in drm_fb_helper_initial_config()
     * to allow driver writes more control over the exact init sequence.
     *
     * Drivers must call drm_fb_helper_prepare() before calling this function.
     *
     * RETURNS:
     * Zero if everything went ok, nonzero otherwise.
     */
    int drm_fb_helper_init(struct drm_device *dev,
    		       struct drm_fb_helper *fb_helper,
    		       int max_conn_count)
    {
    	int ret;
    
    	if (!drm_fbdev_emulation) {
    		dev->fb_helper = fb_helper;
    		return 0;
    	}
    
    	/*
    	 * If this is not the generic fbdev client, initialize a drm_client
    	 * without callbacks so we can use the modesets.
    	 */
    	if (!fb_helper->client.funcs) {
    		ret = drm_client_init(dev, &fb_helper->client, "drm_fb_helper", NULL);
    		if (ret)
    			return ret;
    	}
    
    	dev->fb_helper = fb_helper;
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_init);
    
    /**
     * drm_fb_helper_alloc_fbi - allocate fb_info and some of its members
     * @fb_helper: driver-allocated fbdev helper
     *
     * A helper to alloc fb_info and the members cmap and apertures. Called
     * by the driver within the fb_probe fb_helper callback function. Drivers do not
     * need to release the allocated fb_info structure themselves, this is
     * automatically done when calling drm_fb_helper_fini().
     *
     * RETURNS:
     * fb_info pointer if things went okay, pointer containing error code
     * otherwise
     */
    struct fb_info *drm_fb_helper_alloc_fbi(struct drm_fb_helper *fb_helper)
    {
    	struct device *dev = fb_helper->dev->dev;
    	struct fb_info *info;
    	int ret;
    
    	info = framebuffer_alloc(0, dev);
    	if (!info)
    		return ERR_PTR(-ENOMEM);
    
    	ret = fb_alloc_cmap(&info->cmap, 256, 0);
    	if (ret)
    		goto err_release;
    
    	info->apertures = alloc_apertures(1);
    	if (!info->apertures) {
    		ret = -ENOMEM;
    		goto err_free_cmap;
    	}
    
    	fb_helper->fbdev = info;
    	info->skip_vt_switch = true;
    
    	return info;
    
    err_free_cmap:
    	fb_dealloc_cmap(&info->cmap);
    err_release:
    	framebuffer_release(info);
    	return ERR_PTR(ret);
    }
    EXPORT_SYMBOL(drm_fb_helper_alloc_fbi);
    
    /**
     * drm_fb_helper_unregister_fbi - unregister fb_info framebuffer device
     * @fb_helper: driver-allocated fbdev helper, can be NULL
     *
     * A wrapper around unregister_framebuffer, to release the fb_info
     * framebuffer device. This must be called before releasing all resources for
     * @fb_helper by calling drm_fb_helper_fini().
     */
    void drm_fb_helper_unregister_fbi(struct drm_fb_helper *fb_helper)
    {
    	if (fb_helper && fb_helper->fbdev)
    		unregister_framebuffer(fb_helper->fbdev);
    }
    EXPORT_SYMBOL(drm_fb_helper_unregister_fbi);
    
    /**
     * drm_fb_helper_fini - finialize a &struct drm_fb_helper
     * @fb_helper: driver-allocated fbdev helper, can be NULL
     *
     * This cleans up all remaining resources associated with @fb_helper. Must be
     * called after drm_fb_helper_unlink_fbi() was called.
     */
    void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
    {
    	struct fb_info *info;
    
    	if (!fb_helper)
    		return;
    
    	fb_helper->dev->fb_helper = NULL;
    
    	if (!drm_fbdev_emulation)
    		return;
    
    	cancel_work_sync(&fb_helper->resume_work);
    	cancel_work_sync(&fb_helper->dirty_work);
    
    	info = fb_helper->fbdev;
    	if (info) {
    		if (info->cmap.len)
    			fb_dealloc_cmap(&info->cmap);
    		framebuffer_release(info);
    	}
    	fb_helper->fbdev = NULL;
    
    	mutex_lock(&kernel_fb_helper_lock);
    	if (!list_empty(&fb_helper->kernel_fb_list)) {
    		list_del(&fb_helper->kernel_fb_list);
    		if (list_empty(&kernel_fb_helper_list))
    			unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
    	}
    	mutex_unlock(&kernel_fb_helper_lock);
    
    	mutex_destroy(&fb_helper->lock);
    
    	if (!fb_helper->client.funcs)
    		drm_client_release(&fb_helper->client);
    }
    EXPORT_SYMBOL(drm_fb_helper_fini);
    
    /**
     * drm_fb_helper_unlink_fbi - wrapper around unlink_framebuffer
     * @fb_helper: driver-allocated fbdev helper, can be NULL
     *
     * A wrapper around unlink_framebuffer implemented by fbdev core
     */
    void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
    {
    	if (fb_helper && fb_helper->fbdev)
    		unlink_framebuffer(fb_helper->fbdev);
    }
    EXPORT_SYMBOL(drm_fb_helper_unlink_fbi);
    
    static bool drm_fbdev_use_shadow_fb(struct drm_fb_helper *fb_helper)
    {
    	struct drm_device *dev = fb_helper->dev;
    	struct drm_framebuffer *fb = fb_helper->fb;
    
    	return dev->mode_config.prefer_shadow_fbdev ||
    	       dev->mode_config.prefer_shadow ||
    	       fb->funcs->dirty;
    }
    
    static void drm_fb_helper_dirty(struct fb_info *info, u32 x, u32 y,
    				u32 width, u32 height)
    {
    	struct drm_fb_helper *helper = info->par;
    	struct drm_clip_rect *clip = &helper->dirty_clip;
    	unsigned long flags;
    
    	if (!drm_fbdev_use_shadow_fb(helper))
    		return;
    
    	spin_lock_irqsave(&helper->dirty_lock, flags);
    	clip->x1 = min_t(u32, clip->x1, x);
    	clip->y1 = min_t(u32, clip->y1, y);
    	clip->x2 = max_t(u32, clip->x2, x + width);
    	clip->y2 = max_t(u32, clip->y2, y + height);
    	spin_unlock_irqrestore(&helper->dirty_lock, flags);
    
    	schedule_work(&helper->dirty_work);
    }
    
    /**
     * drm_fb_helper_deferred_io() - fbdev deferred_io callback function
     * @info: fb_info struct pointer
     * @pagelist: list of dirty mmap framebuffer pages
     *
     * This function is used as the &fb_deferred_io.deferred_io
     * callback function for flushing the fbdev mmap writes.
     */
    void drm_fb_helper_deferred_io(struct fb_info *info,
    			       struct list_head *pagelist)
    {
    	unsigned long start, end, min, max;
    	struct page *page;
    	u32 y1, y2;
    
    	min = ULONG_MAX;
    	max = 0;
    	list_for_each_entry(page, pagelist, lru) {
    		start = page->index << PAGE_SHIFT;
    		end = start + PAGE_SIZE - 1;
    		min = min(min, start);
    		max = max(max, end);
    	}
    
    	if (min < max) {
    		y1 = min / info->fix.line_length;
    		y2 = min_t(u32, DIV_ROUND_UP(max, info->fix.line_length),
    			   info->var.yres);
    		drm_fb_helper_dirty(info, 0, y1, info->var.xres, y2 - y1);
    	}
    }
    EXPORT_SYMBOL(drm_fb_helper_deferred_io);
    
    /**
     * drm_fb_helper_defio_init - fbdev deferred I/O initialization
     * @fb_helper: driver-allocated fbdev helper
     *
     * This function allocates &fb_deferred_io, sets callback to
     * drm_fb_helper_deferred_io(), delay to 50ms and calls fb_deferred_io_init().
     * It should be called from the &drm_fb_helper_funcs->fb_probe callback.
     * drm_fb_helper_fbdev_teardown() cleans up deferred I/O.
     *
     * NOTE: A copy of &fb_ops is made and assigned to &info->fbops. This is done
     * because fb_deferred_io_cleanup() clears &fbops->fb_mmap and would thereby
     * affect other instances of that &fb_ops.
     *
     * Returns:
     * 0 on success or a negative error code on failure.
     */
    int drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper)
    {
    	struct fb_info *info = fb_helper->fbdev;
    	struct fb_deferred_io *fbdefio;
    	struct fb_ops *fbops;
    
    	fbdefio = kzalloc(sizeof(*fbdefio), GFP_KERNEL);
    	fbops = kzalloc(sizeof(*fbops), GFP_KERNEL);
    	if (!fbdefio || !fbops) {
    		kfree(fbdefio);
    		kfree(fbops);
    		return -ENOMEM;
    	}
    
    	info->fbdefio = fbdefio;
    	fbdefio->delay = msecs_to_jiffies(50);
    	fbdefio->deferred_io = drm_fb_helper_deferred_io;
    
    	*fbops = *info->fbops;
    	info->fbops = fbops;
    
    	fb_deferred_io_init(info);
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_defio_init);
    
    /**
     * drm_fb_helper_sys_read - wrapper around fb_sys_read
     * @info: fb_info struct pointer
     * @buf: userspace buffer to read from framebuffer memory
     * @count: number of bytes to read from framebuffer memory
     * @ppos: read offset within framebuffer memory
     *
     * A wrapper around fb_sys_read implemented by fbdev core
     */
    ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
    			       size_t count, loff_t *ppos)
    {
    	return fb_sys_read(info, buf, count, ppos);
    }
    EXPORT_SYMBOL(drm_fb_helper_sys_read);
    
    /**
     * drm_fb_helper_sys_write - wrapper around fb_sys_write
     * @info: fb_info struct pointer
     * @buf: userspace buffer to write to framebuffer memory
     * @count: number of bytes to write to framebuffer memory
     * @ppos: write offset within framebuffer memory
     *
     * A wrapper around fb_sys_write implemented by fbdev core
     */
    ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
    				size_t count, loff_t *ppos)
    {
    	ssize_t ret;
    
    	ret = fb_sys_write(info, buf, count, ppos);
    	if (ret > 0)
    		drm_fb_helper_dirty(info, 0, 0, info->var.xres,
    				    info->var.yres);
    
    	return ret;
    }
    EXPORT_SYMBOL(drm_fb_helper_sys_write);
    
    /**
     * drm_fb_helper_sys_fillrect - wrapper around sys_fillrect
     * @info: fbdev registered by the helper
     * @rect: info about rectangle to fill
     *
     * A wrapper around sys_fillrect implemented by fbdev core
     */
    void drm_fb_helper_sys_fillrect(struct fb_info *info,
    				const struct fb_fillrect *rect)
    {
    	sys_fillrect(info, rect);
    	drm_fb_helper_dirty(info, rect->dx, rect->dy,
    			    rect->width, rect->height);
    }
    EXPORT_SYMBOL(drm_fb_helper_sys_fillrect);
    
    /**
     * drm_fb_helper_sys_copyarea - wrapper around sys_copyarea
     * @info: fbdev registered by the helper
     * @area: info about area to copy
     *
     * A wrapper around sys_copyarea implemented by fbdev core
     */
    void drm_fb_helper_sys_copyarea(struct fb_info *info,
    				const struct fb_copyarea *area)
    {
    	sys_copyarea(info, area);
    	drm_fb_helper_dirty(info, area->dx, area->dy,
    			    area->width, area->height);
    }
    EXPORT_SYMBOL(drm_fb_helper_sys_copyarea);
    
    /**
     * drm_fb_helper_sys_imageblit - wrapper around sys_imageblit
     * @info: fbdev registered by the helper
     * @image: info about image to blit
     *
     * A wrapper around sys_imageblit implemented by fbdev core
     */
    void drm_fb_helper_sys_imageblit(struct fb_info *info,
    				 const struct fb_image *image)
    {
    	sys_imageblit(info, image);
    	drm_fb_helper_dirty(info, image->dx, image->dy,
    			    image->width, image->height);
    }
    EXPORT_SYMBOL(drm_fb_helper_sys_imageblit);
    
    /**
     * drm_fb_helper_cfb_fillrect - wrapper around cfb_fillrect
     * @info: fbdev registered by the helper
     * @rect: info about rectangle to fill
     *
     * A wrapper around cfb_fillrect implemented by fbdev core
     */
    void drm_fb_helper_cfb_fillrect(struct fb_info *info,
    				const struct fb_fillrect *rect)
    {
    	cfb_fillrect(info, rect);
    	drm_fb_helper_dirty(info, rect->dx, rect->dy,
    			    rect->width, rect->height);
    }
    EXPORT_SYMBOL(drm_fb_helper_cfb_fillrect);
    
    /**
     * drm_fb_helper_cfb_copyarea - wrapper around cfb_copyarea
     * @info: fbdev registered by the helper
     * @area: info about area to copy
     *
     * A wrapper around cfb_copyarea implemented by fbdev core
     */
    void drm_fb_helper_cfb_copyarea(struct fb_info *info,
    				const struct fb_copyarea *area)
    {
    	cfb_copyarea(info, area);
    	drm_fb_helper_dirty(info, area->dx, area->dy,
    			    area->width, area->height);
    }
    EXPORT_SYMBOL(drm_fb_helper_cfb_copyarea);
    
    /**
     * drm_fb_helper_cfb_imageblit - wrapper around cfb_imageblit
     * @info: fbdev registered by the helper
     * @image: info about image to blit
     *
     * A wrapper around cfb_imageblit implemented by fbdev core
     */
    void drm_fb_helper_cfb_imageblit(struct fb_info *info,
    				 const struct fb_image *image)
    {
    	cfb_imageblit(info, image);
    	drm_fb_helper_dirty(info, image->dx, image->dy,
    			    image->width, image->height);
    }
    EXPORT_SYMBOL(drm_fb_helper_cfb_imageblit);
    
    /**
     * drm_fb_helper_set_suspend - wrapper around fb_set_suspend
     * @fb_helper: driver-allocated fbdev helper, can be NULL
     * @suspend: whether to suspend or resume
     *
     * A wrapper around fb_set_suspend implemented by fbdev core.
     * Use drm_fb_helper_set_suspend_unlocked() if you don't need to take
     * the lock yourself
     */
    void drm_fb_helper_set_suspend(struct drm_fb_helper *fb_helper, bool suspend)
    {
    	if (fb_helper && fb_helper->fbdev)
    		fb_set_suspend(fb_helper->fbdev, suspend);
    }
    EXPORT_SYMBOL(drm_fb_helper_set_suspend);
    
    /**
     * drm_fb_helper_set_suspend_unlocked - wrapper around fb_set_suspend that also
     *                                      takes the console lock
     * @fb_helper: driver-allocated fbdev helper, can be NULL
     * @suspend: whether to suspend or resume
     *
     * A wrapper around fb_set_suspend() that takes the console lock. If the lock
     * isn't available on resume, a worker is tasked with waiting for the lock
     * to become available. The console lock can be pretty contented on resume
     * due to all the printk activity.
     *
     * This function can be called multiple times with the same state since
     * &fb_info.state is checked to see if fbdev is running or not before locking.
     *
     * Use drm_fb_helper_set_suspend() if you need to take the lock yourself.
     */
    void drm_fb_helper_set_suspend_unlocked(struct drm_fb_helper *fb_helper,
    					bool suspend)
    {
    	if (!fb_helper || !fb_helper->fbdev)
    		return;
    
    	/* make sure there's no pending/ongoing resume */
    	flush_work(&fb_helper->resume_work);
    
    	if (suspend) {
    		if (fb_helper->fbdev->state != FBINFO_STATE_RUNNING)
    			return;
    
    		console_lock();
    
    	} else {
    		if (fb_helper->fbdev->state == FBINFO_STATE_RUNNING)
    			return;
    
    		if (!console_trylock()) {
    			schedule_work(&fb_helper->resume_work);
    			return;
    		}
    	}
    
    	fb_set_suspend(fb_helper->fbdev, suspend);
    	console_unlock();
    }
    EXPORT_SYMBOL(drm_fb_helper_set_suspend_unlocked);
    
    static int setcmap_pseudo_palette(struct fb_cmap *cmap, struct fb_info *info)
    {
    	u32 *palette = (u32 *)info->pseudo_palette;
    	int i;
    
    	if (cmap->start + cmap->len > 16)
    		return -EINVAL;
    
    	for (i = 0; i < cmap->len; ++i) {
    		u16 red = cmap->red[i];
    		u16 green = cmap->green[i];
    		u16 blue = cmap->blue[i];
    		u32 value;
    
    		red >>= 16 - info->var.red.length;
    		green >>= 16 - info->var.green.length;
    		blue >>= 16 - info->var.blue.length;
    		value = (red << info->var.red.offset) |
    			(green << info->var.green.offset) |
    			(blue << info->var.blue.offset);
    		if (info->var.transp.length > 0) {
    			u32 mask = (1 << info->var.transp.length) - 1;
    
    			mask <<= info->var.transp.offset;
    			value |= mask;
    		}
    		palette[cmap->start + i] = value;
    	}
    
    	return 0;
    }
    
    static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct drm_mode_set *modeset;
    	struct drm_crtc *crtc;
    	u16 *r, *g, *b;
    	int ret = 0;
    
    	drm_modeset_lock_all(fb_helper->dev);
    	drm_client_for_each_modeset(modeset, &fb_helper->client) {
    		crtc = modeset->crtc;
    		if (!crtc->funcs->gamma_set || !crtc->gamma_size)
    			return -EINVAL;
    
    		if (cmap->start + cmap->len > crtc->gamma_size)
    			return -EINVAL;
    
    		r = crtc->gamma_store;
    		g = r + crtc->gamma_size;
    		b = g + crtc->gamma_size;
    
    		memcpy(r + cmap->start, cmap->red, cmap->len * sizeof(*r));
    		memcpy(g + cmap->start, cmap->green, cmap->len * sizeof(*g));
    		memcpy(b + cmap->start, cmap->blue, cmap->len * sizeof(*b));
    
    		ret = crtc->funcs->gamma_set(crtc, r, g, b,
    					     crtc->gamma_size, NULL);
    		if (ret)
    			return ret;
    	}
    	drm_modeset_unlock_all(fb_helper->dev);
    
    	return ret;
    }
    
    static struct drm_property_blob *setcmap_new_gamma_lut(struct drm_crtc *crtc,
    						       struct fb_cmap *cmap)
    {
    	struct drm_device *dev = crtc->dev;
    	struct drm_property_blob *gamma_lut;
    	struct drm_color_lut *lut;
    	int size = crtc->gamma_size;
    	int i;
    
    	if (!size || cmap->start + cmap->len > size)
    		return ERR_PTR(-EINVAL);
    
    	gamma_lut = drm_property_create_blob(dev, sizeof(*lut) * size, NULL);
    	if (IS_ERR(gamma_lut))
    		return gamma_lut;
    
    	lut = gamma_lut->data;
    	if (cmap->start || cmap->len != size) {
    		u16 *r = crtc->gamma_store;
    		u16 *g = r + crtc->gamma_size;
    		u16 *b = g + crtc->gamma_size;
    
    		for (i = 0; i < cmap->start; i++) {
    			lut[i].red = r[i];
    			lut[i].green = g[i];
    			lut[i].blue = b[i];
    		}
    		for (i = cmap->start + cmap->len; i < size; i++) {
    			lut[i].red = r[i];
    			lut[i].green = g[i];
    			lut[i].blue = b[i];
    		}
    	}
    
    	for (i = 0; i < cmap->len; i++) {
    		lut[cmap->start + i].red = cmap->red[i];
    		lut[cmap->start + i].green = cmap->green[i];
    		lut[cmap->start + i].blue = cmap->blue[i];
    	}
    
    	return gamma_lut;
    }
    
    static int setcmap_atomic(struct fb_cmap *cmap, struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct drm_device *dev = fb_helper->dev;
    	struct drm_property_blob *gamma_lut = NULL;
    	struct drm_modeset_acquire_ctx ctx;
    	struct drm_crtc_state *crtc_state;
    	struct drm_atomic_state *state;
    	struct drm_mode_set *modeset;
    	struct drm_crtc *crtc;
    	u16 *r, *g, *b;
    	bool replaced;
    	int ret = 0;
    
    	drm_modeset_acquire_init(&ctx, 0);
    
    	state = drm_atomic_state_alloc(dev);
    	if (!state) {
    		ret = -ENOMEM;
    		goto out_ctx;
    	}
    
    	state->acquire_ctx = &ctx;
    retry:
    	drm_client_for_each_modeset(modeset, &fb_helper->client) {
    		crtc = modeset->crtc;
    
    		if (!gamma_lut)
    			gamma_lut = setcmap_new_gamma_lut(crtc, cmap);
    		if (IS_ERR(gamma_lut)) {
    			ret = PTR_ERR(gamma_lut);
    			gamma_lut = NULL;
    			goto out_state;
    		}
    
    		crtc_state = drm_atomic_get_crtc_state(state, crtc);
    		if (IS_ERR(crtc_state)) {
    			ret = PTR_ERR(crtc_state);
    			goto out_state;
    		}
    
    		replaced  = drm_property_replace_blob(&crtc_state->degamma_lut,
    						      NULL);
    		replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
    		replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
    						      gamma_lut);
    		crtc_state->color_mgmt_changed |= replaced;
    	}
    
    	ret = drm_atomic_commit(state);
    	if (ret)
    		goto out_state;
    
    	drm_client_for_each_modeset(modeset, &fb_helper->client) {
    		crtc = modeset->crtc;
    
    		r = crtc->gamma_store;
    		g = r + crtc->gamma_size;
    		b = g + crtc->gamma_size;
    
    		memcpy(r + cmap->start, cmap->red, cmap->len * sizeof(*r));
    		memcpy(g + cmap->start, cmap->green, cmap->len * sizeof(*g));
    		memcpy(b + cmap->start, cmap->blue, cmap->len * sizeof(*b));
    	}
    
    out_state:
    	if (ret == -EDEADLK)
    		goto backoff;
    
    	drm_property_blob_put(gamma_lut);
    	drm_atomic_state_put(state);
    out_ctx:
    	drm_modeset_drop_locks(&ctx);
    	drm_modeset_acquire_fini(&ctx);
    
    	return ret;
    
    backoff:
    	drm_atomic_state_clear(state);
    	drm_modeset_backoff(&ctx);
    	goto retry;
    }
    
    /**
     * drm_fb_helper_setcmap - implementation for &fb_ops.fb_setcmap
     * @cmap: cmap to set
     * @info: fbdev registered by the helper
     */
    int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct drm_device *dev = fb_helper->dev;
    	int ret;
    
    	if (oops_in_progress)
    		return -EBUSY;
    
    	mutex_lock(&fb_helper->lock);
    
    	if (!drm_master_internal_acquire(dev)) {
    		ret = -EBUSY;
    		goto unlock;
    	}
    
    	mutex_lock(&fb_helper->client.modeset_mutex);
    	if (info->fix.visual == FB_VISUAL_TRUECOLOR)
    		ret = setcmap_pseudo_palette(cmap, info);
    	else if (drm_drv_uses_atomic_modeset(fb_helper->dev))
    		ret = setcmap_atomic(cmap, info);
    	else
    		ret = setcmap_legacy(cmap, info);
    	mutex_unlock(&fb_helper->client.modeset_mutex);
    
    	drm_master_internal_release(dev);
    unlock:
    	mutex_unlock(&fb_helper->lock);
    
    	return ret;
    }
    EXPORT_SYMBOL(drm_fb_helper_setcmap);
    
    /**
     * drm_fb_helper_ioctl - legacy ioctl implementation
     * @info: fbdev registered by the helper
     * @cmd: ioctl command
     * @arg: ioctl argument
     *
     * A helper to implement the standard fbdev ioctl. Only
     * FBIO_WAITFORVSYNC is implemented for now.
     */
    int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
    			unsigned long arg)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct drm_device *dev = fb_helper->dev;
    	struct drm_crtc *crtc;
    	int ret = 0;
    
    	mutex_lock(&fb_helper->lock);
    	if (!drm_master_internal_acquire(dev)) {
    		ret = -EBUSY;
    		goto unlock;
    	}
    
    	switch (cmd) {
    	case FBIO_WAITFORVSYNC:
    		/*
    		 * Only consider the first CRTC.
    		 *
    		 * This ioctl is supposed to take the CRTC number as
    		 * an argument, but in fbdev times, what that number
    		 * was supposed to be was quite unclear, different
    		 * drivers were passing that argument differently
    		 * (some by reference, some by value), and most of the
    		 * userspace applications were just hardcoding 0 as an
    		 * argument.
    		 *
    		 * The first CRTC should be the integrated panel on
    		 * most drivers, so this is the best choice we can
    		 * make. If we're not smart enough here, one should
    		 * just consider switch the userspace to KMS.
    		 */
    		crtc = fb_helper->client.modesets[0].crtc;
    
    		/*
    		 * Only wait for a vblank event if the CRTC is
    		 * enabled, otherwise just don't do anythintg,
    		 * not even report an error.
    		 */
    		ret = drm_crtc_vblank_get(crtc);
    		if (!ret) {
    			drm_crtc_wait_one_vblank(crtc);
    			drm_crtc_vblank_put(crtc);
    		}
    
    		ret = 0;
    		break;
    	default:
    		ret = -ENOTTY;
    	}
    
    	drm_master_internal_release(dev);
    unlock:
    	mutex_unlock(&fb_helper->lock);
    	return ret;
    }
    EXPORT_SYMBOL(drm_fb_helper_ioctl);
    
    static bool drm_fb_pixel_format_equal(const struct fb_var_screeninfo *var_1,
    				      const struct fb_var_screeninfo *var_2)
    {
    	return var_1->bits_per_pixel == var_2->bits_per_pixel &&
    	       var_1->grayscale == var_2->grayscale &&
    	       var_1->red.offset == var_2->red.offset &&
    	       var_1->red.length == var_2->red.length &&
    	       var_1->red.msb_right == var_2->red.msb_right &&
    	       var_1->green.offset == var_2->green.offset &&
    	       var_1->green.length == var_2->green.length &&
    	       var_1->green.msb_right == var_2->green.msb_right &&
    	       var_1->blue.offset == var_2->blue.offset &&
    	       var_1->blue.length == var_2->blue.length &&
    	       var_1->blue.msb_right == var_2->blue.msb_right &&
    	       var_1->transp.offset == var_2->transp.offset &&
    	       var_1->transp.length == var_2->transp.length &&
    	       var_1->transp.msb_right == var_2->transp.msb_right;
    }
    
    static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
    					 u8 depth)
    {
    	switch (depth) {
    	case 8:
    		var->red.offset = 0;
    		var->green.offset = 0;
    		var->blue.offset = 0;
    		var->red.length = 8; /* 8bit DAC */
    		var->green.length = 8;
    		var->blue.length = 8;
    		var->transp.offset = 0;
    		var->transp.length = 0;
    		break;
    	case 15:
    		var->red.offset = 10;
    		var->green.offset = 5;
    		var->blue.offset = 0;
    		var->red.length = 5;
    		var->green.length = 5;
    		var->blue.length = 5;
    		var->transp.offset = 15;
    		var->transp.length = 1;
    		break;
    	case 16:
    		var->red.offset = 11;
    		var->green.offset = 5;
    		var->blue.offset = 0;
    		var->red.length = 5;
    		var->green.length = 6;
    		var->blue.length = 5;
    		var->transp.offset = 0;
    		break;
    	case 24:
    		var->red.offset = 16;
    		var->green.offset = 8;
    		var->blue.offset = 0;
    		var->red.length = 8;
    		var->green.length = 8;
    		var->blue.length = 8;
    		var->transp.offset = 0;
    		var->transp.length = 0;
    		break;
    	case 32:
    		var->red.offset = 16;
    		var->green.offset = 8;
    		var->blue.offset = 0;
    		var->red.length = 8;
    		var->green.length = 8;
    		var->blue.length = 8;
    		var->transp.offset = 24;
    		var->transp.length = 8;
    		break;
    	default:
    		break;
    	}
    }
    
    /**
     * drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
     * @var: screeninfo to check
     * @info: fbdev registered by the helper
     */
    int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
    			    struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct drm_framebuffer *fb = fb_helper->fb;
    
    	if (in_dbg_master())
    		return -EINVAL;
    
    	if (var->pixclock != 0) {
    		DRM_DEBUG("fbdev emulation doesn't support changing the pixel clock, value of pixclock is ignored\n");
    		var->pixclock = 0;
    	}
    
    	if ((drm_format_info_block_width(fb->format, 0) > 1) ||
    	    (drm_format_info_block_height(fb->format, 0) > 1))
    		return -EINVAL;
    
    	/*
    	 * Changes struct fb_var_screeninfo are currently not pushed back
    	 * to KMS, hence fail if different settings are requested.
    	 */
    	if (var->bits_per_pixel != fb->format->cpp[0] * 8 ||
    	    var->xres > fb->width || var->yres > fb->height ||
    	    var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
    		DRM_DEBUG("fb requested width/height/bpp can't fit in current fb "
    			  "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
    			  var->xres, var->yres, var->bits_per_pixel,
    			  var->xres_virtual, var->yres_virtual,
    			  fb->width, fb->height, fb->format->cpp[0] * 8);
    		return -EINVAL;
    	}
    
    	/*
    	 * Workaround for SDL 1.2, which is known to be setting all pixel format
    	 * fields values to zero in some cases. We treat this situation as a
    	 * kind of "use some reasonable autodetected values".
    	 */
    	if (!var->red.offset     && !var->green.offset    &&
    	    !var->blue.offset    && !var->transp.offset   &&
    	    !var->red.length     && !var->green.length    &&
    	    !var->blue.length    && !var->transp.length   &&
    	    !var->red.msb_right  && !var->green.msb_right &&
    	    !var->blue.msb_right && !var->transp.msb_right) {
    		drm_fb_helper_fill_pixel_fmt(var, fb->format->depth);
    	}
    
    	/*
    	 * drm fbdev emulation doesn't support changing the pixel format at all,
    	 * so reject all pixel format changing requests.
    	 */
    	if (!drm_fb_pixel_format_equal(var, &info->var)) {
    		DRM_DEBUG("fbdev emulation doesn't support changing the pixel format\n");
    		return -EINVAL;
    	}
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_check_var);
    
    /**
     * drm_fb_helper_set_par - implementation for &fb_ops.fb_set_par
     * @info: fbdev registered by the helper
     *
     * This will let fbcon do the mode init and is called at initialization time by
     * the fbdev core when registering the driver, and later on through the hotplug
     * callback.
     */
    int drm_fb_helper_set_par(struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct fb_var_screeninfo *var = &info->var;
    
    	if (oops_in_progress)
    		return -EBUSY;
    
    	if (var->pixclock != 0) {
    		DRM_ERROR("PIXEL CLOCK SET\n");
    		return -EINVAL;
    	}
    
    	drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper);
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_set_par);
    
    static void pan_set(struct drm_fb_helper *fb_helper, int x, int y)
    {
    	struct drm_mode_set *mode_set;
    
    	mutex_lock(&fb_helper->client.modeset_mutex);
    	drm_client_for_each_modeset(mode_set, &fb_helper->client) {
    		mode_set->x = x;
    		mode_set->y = y;
    	}
    	mutex_unlock(&fb_helper->client.modeset_mutex);
    }
    
    static int pan_display_atomic(struct fb_var_screeninfo *var,
    			      struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	int ret;
    
    	pan_set(fb_helper, var->xoffset, var->yoffset);
    
    	ret = drm_client_modeset_commit_force(&fb_helper->client);
    	if (!ret) {
    		info->var.xoffset = var->xoffset;
    		info->var.yoffset = var->yoffset;
    	} else
    		pan_set(fb_helper, info->var.xoffset, info->var.yoffset);
    
    	return ret;
    }
    
    static int pan_display_legacy(struct fb_var_screeninfo *var,
    			      struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct drm_client_dev *client = &fb_helper->client;
    	struct drm_mode_set *modeset;
    	int ret = 0;
    
    	mutex_lock(&client->modeset_mutex);
    	drm_modeset_lock_all(fb_helper->dev);
    	drm_client_for_each_modeset(modeset, client) {
    		modeset->x = var->xoffset;
    		modeset->y = var->yoffset;
    
    		if (modeset->num_connectors) {
    			ret = drm_mode_set_config_internal(modeset);
    			if (!ret) {
    				info->var.xoffset = var->xoffset;
    				info->var.yoffset = var->yoffset;
    			}
    		}
    	}
    	drm_modeset_unlock_all(fb_helper->dev);
    	mutex_unlock(&client->modeset_mutex);
    
    	return ret;
    }
    
    /**
     * drm_fb_helper_pan_display - implementation for &fb_ops.fb_pan_display
     * @var: updated screen information
     * @info: fbdev registered by the helper
     */
    int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
    			      struct fb_info *info)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    	struct drm_device *dev = fb_helper->dev;
    	int ret;
    
    	if (oops_in_progress)
    		return -EBUSY;
    
    	mutex_lock(&fb_helper->lock);
    	if (!drm_master_internal_acquire(dev)) {
    		ret = -EBUSY;
    		goto unlock;
    	}
    
    	if (drm_drv_uses_atomic_modeset(dev))
    		ret = pan_display_atomic(var, info);
    	else
    		ret = pan_display_legacy(var, info);
    
    	drm_master_internal_release(dev);
    unlock:
    	mutex_unlock(&fb_helper->lock);
    
    	return ret;
    }
    EXPORT_SYMBOL(drm_fb_helper_pan_display);
    
    /*
     * Allocates the backing storage and sets up the fbdev info structure through
     * the ->fb_probe callback.
     */
    static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
    					 int preferred_bpp)
    {
    	struct drm_client_dev *client = &fb_helper->client;
    	int ret = 0;
    	int crtc_count = 0;
    	struct drm_connector_list_iter conn_iter;
    	struct drm_fb_helper_surface_size sizes;
    	struct drm_connector *connector;
    	struct drm_mode_set *mode_set;
    	int best_depth = 0;
    
    	memset(&sizes, 0, sizeof(struct drm_fb_helper_surface_size));
    	sizes.surface_depth = 24;
    	sizes.surface_bpp = 32;
    	sizes.fb_width = (u32)-1;
    	sizes.fb_height = (u32)-1;
    
    	/*
    	 * If driver picks 8 or 16 by default use that for both depth/bpp
    	 * to begin with
    	 */
    	if (preferred_bpp != sizes.surface_bpp)
    		sizes.surface_depth = sizes.surface_bpp = preferred_bpp;
    
    	drm_connector_list_iter_begin(fb_helper->dev, &conn_iter);
    	drm_client_for_each_connector_iter(connector, &conn_iter) {
    		struct drm_cmdline_mode *cmdline_mode;
    
    		cmdline_mode = &connector->cmdline_mode;
    
    		if (cmdline_mode->bpp_specified) {
    			switch (cmdline_mode->bpp) {
    			case 8:
    				sizes.surface_depth = sizes.surface_bpp = 8;
    				break;
    			case 15:
    				sizes.surface_depth = 15;
    				sizes.surface_bpp = 16;
    				break;
    			case 16:
    				sizes.surface_depth = sizes.surface_bpp = 16;
    				break;
    			case 24:
    				sizes.surface_depth = sizes.surface_bpp = 24;
    				break;
    			case 32:
    				sizes.surface_depth = 24;
    				sizes.surface_bpp = 32;
    				break;
    			}
    			break;
    		}
    	}
    	drm_connector_list_iter_end(&conn_iter);
    
    	/*
    	 * If we run into a situation where, for example, the primary plane
    	 * supports RGBA5551 (16 bpp, depth 15) but not RGB565 (16 bpp, depth
    	 * 16) we need to scale down the depth of the sizes we request.
    	 */
    	mutex_lock(&client->modeset_mutex);
    	drm_client_for_each_modeset(mode_set, client) {
    		struct drm_crtc *crtc = mode_set->crtc;
    		struct drm_plane *plane = crtc->primary;
    		int j;
    
    		DRM_DEBUG("test CRTC %u primary plane\n", drm_crtc_index(crtc));
    
    		for (j = 0; j < plane->format_count; j++) {
    			const struct drm_format_info *fmt;
    
    			fmt = drm_format_info(plane->format_types[j]);
    
    			/*
    			 * Do not consider YUV or other complicated formats
    			 * for framebuffers. This means only legacy formats
    			 * are supported (fmt->depth is a legacy field) but
    			 * the framebuffer emulation can only deal with such
    			 * formats, specifically RGB/BGA formats.
    			 */
    			if (fmt->depth == 0)
    				continue;
    
    			/* We found a perfect fit, great */
    			if (fmt->depth == sizes.surface_depth) {
    				best_depth = fmt->depth;
    				break;
    			}
    
    			/* Skip depths above what we're looking for */
    			if (fmt->depth > sizes.surface_depth)
    				continue;
    
    			/* Best depth found so far */
    			if (fmt->depth > best_depth)
    				best_depth = fmt->depth;
    		}
    	}
    	if (sizes.surface_depth != best_depth && best_depth) {
    		DRM_INFO("requested bpp %d, scaled depth down to %d",
    			 sizes.surface_bpp, best_depth);
    		sizes.surface_depth = best_depth;
    	}
    
    	/* first up get a count of crtcs now in use and new min/maxes width/heights */
    	crtc_count = 0;
    	drm_client_for_each_modeset(mode_set, client) {
    		struct drm_display_mode *desired_mode;
    		int x, y, j;
    		/* in case of tile group, are we the last tile vert or horiz?
    		 * If no tile group you are always the last one both vertically
    		 * and horizontally
    		 */
    		bool lastv = true, lasth = true;
    
    		desired_mode = mode_set->mode;
    
    		if (!desired_mode)
    			continue;
    
    		crtc_count++;
    
    		x = mode_set->x;
    		y = mode_set->y;
    
    		sizes.surface_width  = max_t(u32, desired_mode->hdisplay + x, sizes.surface_width);
    		sizes.surface_height = max_t(u32, desired_mode->vdisplay + y, sizes.surface_height);
    
    		for (j = 0; j < mode_set->num_connectors; j++) {
    			struct drm_connector *connector = mode_set->connectors[j];
    
    			if (connector->has_tile) {
    				lasth = (connector->tile_h_loc == (connector->num_h_tile - 1));
    				lastv = (connector->tile_v_loc == (connector->num_v_tile - 1));
    				/* cloning to multiple tiles is just crazy-talk, so: */
    				break;
    			}
    		}
    
    		if (lasth)
    			sizes.fb_width  = min_t(u32, desired_mode->hdisplay + x, sizes.fb_width);
    		if (lastv)
    			sizes.fb_height = min_t(u32, desired_mode->vdisplay + y, sizes.fb_height);
    	}
    	mutex_unlock(&client->modeset_mutex);
    
    	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
    		DRM_INFO("Cannot find any crtc or sizes\n");
    
    		/* First time: disable all crtc's.. */
    		if (!fb_helper->deferred_setup)
    			drm_client_modeset_commit(client);
    		return -EAGAIN;
    	}
    
    	/* Handle our overallocation */
    	sizes.surface_height *= drm_fbdev_overalloc;
    	sizes.surface_height /= 100;
    
    	/* push down into drivers */
    	ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
    	if (ret < 0)
    		return ret;
    
    	strcpy(fb_helper->fb->comm, "[fbcon]");
    	return 0;
    }
    
    static void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
    				   uint32_t depth)
    {
    	info->fix.type = FB_TYPE_PACKED_PIXELS;
    	info->fix.visual = depth == 8 ? FB_VISUAL_PSEUDOCOLOR :
    		FB_VISUAL_TRUECOLOR;
    	info->fix.mmio_start = 0;
    	info->fix.mmio_len = 0;
    	info->fix.type_aux = 0;
    	info->fix.xpanstep = 1; /* doing it in hw */
    	info->fix.ypanstep = 1; /* doing it in hw */
    	info->fix.ywrapstep = 0;
    	info->fix.accel = FB_ACCEL_NONE;
    
    	info->fix.line_length = pitch;
    }
    
    static void drm_fb_helper_fill_var(struct fb_info *info,
    				   struct drm_fb_helper *fb_helper,
    				   uint32_t fb_width, uint32_t fb_height)
    {
    	struct drm_framebuffer *fb = fb_helper->fb;
    
    	WARN_ON((drm_format_info_block_width(fb->format, 0) > 1) ||
    		(drm_format_info_block_height(fb->format, 0) > 1));
    	info->pseudo_palette = fb_helper->pseudo_palette;
    	info->var.xres_virtual = fb->width;
    	info->var.yres_virtual = fb->height;
    	info->var.bits_per_pixel = fb->format->cpp[0] * 8;
    	info->var.accel_flags = FB_ACCELF_TEXT;
    	info->var.xoffset = 0;
    	info->var.yoffset = 0;
    	info->var.activate = FB_ACTIVATE_NOW;
    
    	drm_fb_helper_fill_pixel_fmt(&info->var, fb->format->depth);
    
    	info->var.xres = fb_width;
    	info->var.yres = fb_height;
    }
    
    /**
     * drm_fb_helper_fill_info - initializes fbdev information
     * @info: fbdev instance to set up
     * @fb_helper: fb helper instance to use as template
     * @sizes: describes fbdev size and scanout surface size
     *
     * Sets up the variable and fixed fbdev metainformation from the given fb helper
     * instance and the drm framebuffer allocated in &drm_fb_helper.fb.
     *
     * Drivers should call this (or their equivalent setup code) from their
     * &drm_fb_helper_funcs.fb_probe callback after having allocated the fbdev
     * backing storage framebuffer.
     */
    void drm_fb_helper_fill_info(struct fb_info *info,
    			     struct drm_fb_helper *fb_helper,
    			     struct drm_fb_helper_surface_size *sizes)
    {
    	struct drm_framebuffer *fb = fb_helper->fb;
    
    	drm_fb_helper_fill_fix(info, fb->pitches[0], fb->format->depth);
    	drm_fb_helper_fill_var(info, fb_helper,
    			       sizes->fb_width, sizes->fb_height);
    
    	info->par = fb_helper;
    	snprintf(info->fix.id, sizeof(info->fix.id), "%sdrmfb",
    		 fb_helper->dev->driver->name);
    
    }
    EXPORT_SYMBOL(drm_fb_helper_fill_info);
    
    /*
     * This is a continuation of drm_setup_crtcs() that sets up anything related
     * to the framebuffer. During initialization, drm_setup_crtcs() is called before
     * the framebuffer has been allocated (fb_helper->fb and fb_helper->fbdev).
     * So, any setup that touches those fields needs to be done here instead of in
     * drm_setup_crtcs().
     */
    static void drm_setup_crtcs_fb(struct drm_fb_helper *fb_helper)
    {
    	struct drm_client_dev *client = &fb_helper->client;
    	struct drm_connector_list_iter conn_iter;
    	struct fb_info *info = fb_helper->fbdev;
    	unsigned int rotation, sw_rotations = 0;
    	struct drm_connector *connector;
    	struct drm_mode_set *modeset;
    
    	mutex_lock(&client->modeset_mutex);
    	drm_client_for_each_modeset(modeset, client) {
    		if (!modeset->num_connectors)
    			continue;
    
    		modeset->fb = fb_helper->fb;
    
    		if (drm_client_rotation(modeset, &rotation))
    			/* Rotating in hardware, fbcon should not rotate */
    			sw_rotations |= DRM_MODE_ROTATE_0;
    		else
    			sw_rotations |= rotation;
    	}
    	mutex_unlock(&client->modeset_mutex);
    
    	drm_connector_list_iter_begin(fb_helper->dev, &conn_iter);
    	drm_client_for_each_connector_iter(connector, &conn_iter) {
    
    		/* use first connected connector for the physical dimensions */
    		if (connector->status == connector_status_connected) {
    			info->var.width = connector->display_info.width_mm;
    			info->var.height = connector->display_info.height_mm;
    			break;
    		}
    	}
    	drm_connector_list_iter_end(&conn_iter);
    
    	switch (sw_rotations) {
    	case DRM_MODE_ROTATE_0:
    		info->fbcon_rotate_hint = FB_ROTATE_UR;
    		break;
    	case DRM_MODE_ROTATE_90:
    		info->fbcon_rotate_hint = FB_ROTATE_CCW;
    		break;
    	case DRM_MODE_ROTATE_180:
    		info->fbcon_rotate_hint = FB_ROTATE_UD;
    		break;
    	case DRM_MODE_ROTATE_270:
    		info->fbcon_rotate_hint = FB_ROTATE_CW;
    		break;
    	default:
    		/*
    		 * Multiple bits are set / multiple rotations requested
    		 * fbcon cannot handle separate rotation settings per
    		 * output, so fallback to unrotated.
    		 */
    		info->fbcon_rotate_hint = FB_ROTATE_UR;
    	}
    }
    
    /* Note: Drops fb_helper->lock before returning. */
    static int
    __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper,
    					  int bpp_sel)
    {
    	struct drm_device *dev = fb_helper->dev;
    	struct fb_info *info;
    	unsigned int width, height;
    	int ret;
    
    	width = dev->mode_config.max_width;
    	height = dev->mode_config.max_height;
    
    	drm_client_modeset_probe(&fb_helper->client, width, height);
    	ret = drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
    	if (ret < 0) {
    		if (ret == -EAGAIN) {
    			fb_helper->preferred_bpp = bpp_sel;
    			fb_helper->deferred_setup = true;
    			ret = 0;
    		}
    		mutex_unlock(&fb_helper->lock);
    
    		return ret;
    	}
    	drm_setup_crtcs_fb(fb_helper);
    
    	fb_helper->deferred_setup = false;
    
    	info = fb_helper->fbdev;
    	info->var.pixclock = 0;
    	/* Shamelessly allow physical address leaking to userspace */
    #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
    	if (!drm_leak_fbdev_smem)
    #endif
    		/* don't leak any physical addresses to userspace */
    		info->flags |= FBINFO_HIDE_SMEM_START;
    
    	/* Need to drop locks to avoid recursive deadlock in
    	 * register_framebuffer. This is ok because the only thing left to do is
    	 * register the fbdev emulation instance in kernel_fb_helper_list. */
    	mutex_unlock(&fb_helper->lock);
    
    	ret = register_framebuffer(info);
    	if (ret < 0)
    		return ret;
    
    	dev_info(dev->dev, "fb%d: %s frame buffer device\n",
    		 info->node, info->fix.id);
    
    	mutex_lock(&kernel_fb_helper_lock);
    	if (list_empty(&kernel_fb_helper_list))
    		register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
    
    	list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
    	mutex_unlock(&kernel_fb_helper_lock);
    
    	return 0;
    }
    
    /**
     * drm_fb_helper_initial_config - setup a sane initial connector configuration
     * @fb_helper: fb_helper device struct
     * @bpp_sel: bpp value to use for the framebuffer configuration
     *
     * Scans the CRTCs and connectors and tries to put together an initial setup.
     * At the moment, this is a cloned configuration across all heads with
     * a new framebuffer object as the backing store.
     *
     * Note that this also registers the fbdev and so allows userspace to call into
     * the driver through the fbdev interfaces.
     *
     * This function will call down into the &drm_fb_helper_funcs.fb_probe callback
     * to let the driver allocate and initialize the fbdev info structure and the
     * drm framebuffer used to back the fbdev. drm_fb_helper_fill_info() is provided
     * as a helper to setup simple default values for the fbdev info structure.
     *
     * HANG DEBUGGING:
     *
     * When you have fbcon support built-in or already loaded, this function will do
     * a full modeset to setup the fbdev console. Due to locking misdesign in the
     * VT/fbdev subsystem that entire modeset sequence has to be done while holding
     * console_lock. Until console_unlock is called no dmesg lines will be sent out
     * to consoles, not even serial console. This means when your driver crashes,
     * you will see absolutely nothing else but a system stuck in this function,
     * with no further output. Any kind of printk() you place within your own driver
     * or in the drm core modeset code will also never show up.
     *
     * Standard debug practice is to run the fbcon setup without taking the
     * console_lock as a hack, to be able to see backtraces and crashes on the
     * serial line. This can be done by setting the fb.lockless_register_fb=1 kernel
     * cmdline option.
     *
     * The other option is to just disable fbdev emulation since very likely the
     * first modeset from userspace will crash in the same way, and is even easier
     * to debug. This can be done by setting the drm_kms_helper.fbdev_emulation=0
     * kernel cmdline option.
     *
     * RETURNS:
     * Zero if everything went ok, nonzero otherwise.
     */
    int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
    {
    	int ret;
    
    	if (!drm_fbdev_emulation)
    		return 0;
    
    	mutex_lock(&fb_helper->lock);
    	ret = __drm_fb_helper_initial_config_and_unlock(fb_helper, bpp_sel);
    
    	return ret;
    }
    EXPORT_SYMBOL(drm_fb_helper_initial_config);
    
    /**
     * drm_fb_helper_hotplug_event - respond to a hotplug notification by
     *                               probing all the outputs attached to the fb
     * @fb_helper: driver-allocated fbdev helper, can be NULL
     *
     * Scan the connectors attached to the fb_helper and try to put together a
     * setup after notification of a change in output configuration.
     *
     * Called at runtime, takes the mode config locks to be able to check/change the
     * modeset configuration. Must be run from process context (which usually means
     * either the output polling work or a work item launched from the driver's
     * hotplug interrupt).
     *
     * Note that drivers may call this even before calling
     * drm_fb_helper_initial_config but only after drm_fb_helper_init. This allows
     * for a race-free fbcon setup and will make sure that the fbdev emulation will
     * not miss any hotplug events.
     *
     * RETURNS:
     * 0 on success and a non-zero error code otherwise.
     */
    int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
    {
    	int err = 0;
    
    	if (!drm_fbdev_emulation || !fb_helper)
    		return 0;
    
    	mutex_lock(&fb_helper->lock);
    	if (fb_helper->deferred_setup) {
    		err = __drm_fb_helper_initial_config_and_unlock(fb_helper,
    				fb_helper->preferred_bpp);
    		return err;
    	}
    
    	if (!fb_helper->fb || !drm_master_internal_acquire(fb_helper->dev)) {
    		fb_helper->delayed_hotplug = true;
    		mutex_unlock(&fb_helper->lock);
    		return err;
    	}
    
    	drm_master_internal_release(fb_helper->dev);
    
    	DRM_DEBUG_KMS("\n");
    
    	drm_client_modeset_probe(&fb_helper->client, fb_helper->fb->width, fb_helper->fb->height);
    	drm_setup_crtcs_fb(fb_helper);
    	mutex_unlock(&fb_helper->lock);
    
    	drm_fb_helper_set_par(fb_helper->fbdev);
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_hotplug_event);
    
    /**
     * drm_fb_helper_fbdev_setup() - Setup fbdev emulation
     * @dev: DRM device
     * @fb_helper: fbdev helper structure to set up
     * @funcs: fbdev helper functions
     * @preferred_bpp: Preferred bits per pixel for the device.
     *                 @dev->mode_config.preferred_depth is used if this is zero.
     * @max_conn_count: Maximum number of connectors (not used)
     *
     * This function sets up fbdev emulation and registers fbdev for access by
     * userspace. If all connectors are disconnected, setup is deferred to the next
     * time drm_fb_helper_hotplug_event() is called.
     * The caller must to provide a &drm_fb_helper_funcs->fb_probe callback
     * function.
     *
     * Use drm_fb_helper_fbdev_teardown() to destroy the fbdev.
     *
     * See also: drm_fb_helper_initial_config(), drm_fbdev_generic_setup().
     *
     * Returns:
     * Zero on success or negative error code on failure.
     */
    int drm_fb_helper_fbdev_setup(struct drm_device *dev,
    			      struct drm_fb_helper *fb_helper,
    			      const struct drm_fb_helper_funcs *funcs,
    			      unsigned int preferred_bpp,
    			      unsigned int max_conn_count)
    {
    	int ret;
    
    	if (!preferred_bpp)
    		preferred_bpp = dev->mode_config.preferred_depth;
    	if (!preferred_bpp)
    		preferred_bpp = 32;
    
    	drm_fb_helper_prepare(dev, fb_helper, funcs);
    
    	ret = drm_fb_helper_init(dev, fb_helper, 0);
    	if (ret < 0) {
    		DRM_DEV_ERROR(dev->dev, "fbdev: Failed to initialize (ret=%d)\n", ret);
    		return ret;
    	}
    
    	if (!drm_drv_uses_atomic_modeset(dev))
    		drm_helper_disable_unused_functions(dev);
    
    	ret = drm_fb_helper_initial_config(fb_helper, preferred_bpp);
    	if (ret < 0) {
    		DRM_DEV_ERROR(dev->dev, "fbdev: Failed to set configuration (ret=%d)\n", ret);
    		goto err_drm_fb_helper_fini;
    	}
    
    	return 0;
    
    err_drm_fb_helper_fini:
    	drm_fb_helper_fbdev_teardown(dev);
    
    	return ret;
    }
    EXPORT_SYMBOL(drm_fb_helper_fbdev_setup);
    
    /**
     * drm_fb_helper_fbdev_teardown - Tear down fbdev emulation
     * @dev: DRM device
     *
     * This function unregisters fbdev if not already done and cleans up the
     * associated resources including the &drm_framebuffer.
     * The driver is responsible for freeing the &drm_fb_helper structure which is
     * stored in &drm_device->fb_helper. Do note that this pointer has been cleared
     * when this function returns.
     *
     * In order to support device removal/unplug while file handles are still open,
     * drm_fb_helper_unregister_fbi() should be called on device removal and
     * drm_fb_helper_fbdev_teardown() in the &drm_driver->release callback when
     * file handles are closed.
     */
    void drm_fb_helper_fbdev_teardown(struct drm_device *dev)
    {
    	struct drm_fb_helper *fb_helper = dev->fb_helper;
    	struct fb_ops *fbops = NULL;
    
    	if (!fb_helper)
    		return;
    
    	/* Unregister if it hasn't been done already */
    	if (fb_helper->fbdev && fb_helper->fbdev->dev)
    		drm_fb_helper_unregister_fbi(fb_helper);
    
    	if (fb_helper->fbdev && fb_helper->fbdev->fbdefio) {
    		fb_deferred_io_cleanup(fb_helper->fbdev);
    		kfree(fb_helper->fbdev->fbdefio);
    		fbops = fb_helper->fbdev->fbops;
    	}
    
    	drm_fb_helper_fini(fb_helper);
    	kfree(fbops);
    
    	if (fb_helper->fb)
    		drm_framebuffer_remove(fb_helper->fb);
    }
    EXPORT_SYMBOL(drm_fb_helper_fbdev_teardown);
    
    /**
     * drm_fb_helper_lastclose - DRM driver lastclose helper for fbdev emulation
     * @dev: DRM device
     *
     * This function can be used as the &drm_driver->lastclose callback for drivers
     * that only need to call drm_fb_helper_restore_fbdev_mode_unlocked().
     */
    void drm_fb_helper_lastclose(struct drm_device *dev)
    {
    	drm_fb_helper_restore_fbdev_mode_unlocked(dev->fb_helper);
    }
    EXPORT_SYMBOL(drm_fb_helper_lastclose);
    
    /**
     * drm_fb_helper_output_poll_changed - DRM mode config \.output_poll_changed
     *                                     helper for fbdev emulation
     * @dev: DRM device
     *
     * This function can be used as the
     * &drm_mode_config_funcs.output_poll_changed callback for drivers that only
     * need to call drm_fb_helper_hotplug_event().
     */
    void drm_fb_helper_output_poll_changed(struct drm_device *dev)
    {
    	drm_fb_helper_hotplug_event(dev->fb_helper);
    }
    EXPORT_SYMBOL(drm_fb_helper_output_poll_changed);
    
    /* @user: 1=userspace, 0=fbcon */
    static int drm_fbdev_fb_open(struct fb_info *info, int user)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    
    	/* No need to take a ref for fbcon because it unbinds on unregister */
    	if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
    		return -ENODEV;
    
    	return 0;
    }
    
    static int drm_fbdev_fb_release(struct fb_info *info, int user)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    
    	if (user)
    		module_put(fb_helper->dev->driver->fops->owner);
    
    	return 0;
    }
    
    static void drm_fbdev_cleanup(struct drm_fb_helper *fb_helper)
    {
    	struct fb_info *fbi = fb_helper->fbdev;
    	struct fb_ops *fbops = NULL;
    	void *shadow = NULL;
    
    	if (!fb_helper->dev)
    		return;
    
    	if (fbi && fbi->fbdefio) {
    		fb_deferred_io_cleanup(fbi);
    		shadow = fbi->screen_buffer;
    		fbops = fbi->fbops;
    	}
    
    	drm_fb_helper_fini(fb_helper);
    
    	if (shadow) {
    		vfree(shadow);
    		kfree(fbops);
    	}
    
    	drm_client_framebuffer_delete(fb_helper->buffer);
    }
    
    static void drm_fbdev_release(struct drm_fb_helper *fb_helper)
    {
    	drm_fbdev_cleanup(fb_helper);
    	drm_client_release(&fb_helper->client);
    	kfree(fb_helper);
    }
    
    /*
     * fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
     * unregister_framebuffer() or fb_release().
     */
    static void drm_fbdev_fb_destroy(struct fb_info *info)
    {
    	drm_fbdev_release(info->par);
    }
    
    static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
    {
    	struct drm_fb_helper *fb_helper = info->par;
    
    	if (fb_helper->dev->driver->gem_prime_mmap)
    		return fb_helper->dev->driver->gem_prime_mmap(fb_helper->buffer->gem, vma);
    	else
    		return -ENODEV;
    }
    
    static struct fb_ops drm_fbdev_fb_ops = {
    	.owner		= THIS_MODULE,
    	DRM_FB_HELPER_DEFAULT_OPS,
    	.fb_open	= drm_fbdev_fb_open,
    	.fb_release	= drm_fbdev_fb_release,
    	.fb_destroy	= drm_fbdev_fb_destroy,
    	.fb_mmap	= drm_fbdev_fb_mmap,
    	.fb_read	= drm_fb_helper_sys_read,
    	.fb_write	= drm_fb_helper_sys_write,
    	.fb_fillrect	= drm_fb_helper_sys_fillrect,
    	.fb_copyarea	= drm_fb_helper_sys_copyarea,
    	.fb_imageblit	= drm_fb_helper_sys_imageblit,
    };
    
    static struct fb_deferred_io drm_fbdev_defio = {
    	.delay		= HZ / 20,
    	.deferred_io	= drm_fb_helper_deferred_io,
    };
    
    /**
     * drm_fb_helper_generic_probe - Generic fbdev emulation probe helper
     * @fb_helper: fbdev helper structure
     * @sizes: describes fbdev size and scanout surface size
     *
     * This function uses the client API to create a framebuffer backed by a dumb buffer.
     *
     * The _sys_ versions are used for &fb_ops.fb_read, fb_write, fb_fillrect,
     * fb_copyarea, fb_imageblit.
     *
     * Returns:
     * Zero on success or negative error code on failure.
     */
    int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
    				struct drm_fb_helper_surface_size *sizes)
    {
    	struct drm_client_dev *client = &fb_helper->client;
    	struct drm_client_buffer *buffer;
    	struct drm_framebuffer *fb;
    	struct fb_info *fbi;
    	u32 format;
    	void *vaddr;
    
    	DRM_DEBUG_KMS("surface width(%d), height(%d) and bpp(%d)\n",
    		      sizes->surface_width, sizes->surface_height,
    		      sizes->surface_bpp);
    
    	format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
    	buffer = drm_client_framebuffer_create(client, sizes->surface_width,
    					       sizes->surface_height, format);
    	if (IS_ERR(buffer))
    		return PTR_ERR(buffer);
    
    	fb_helper->buffer = buffer;
    	fb_helper->fb = buffer->fb;
    	fb = buffer->fb;
    
    	fbi = drm_fb_helper_alloc_fbi(fb_helper);
    	if (IS_ERR(fbi))
    		return PTR_ERR(fbi);
    
    	fbi->fbops = &drm_fbdev_fb_ops;
    	fbi->screen_size = fb->height * fb->pitches[0];
    	fbi->fix.smem_len = fbi->screen_size;
    
    	drm_fb_helper_fill_info(fbi, fb_helper, sizes);
    
    	if (drm_fbdev_use_shadow_fb(fb_helper)) {
    		struct fb_ops *fbops;
    		void *shadow;
    
    		/*
    		 * fb_deferred_io_cleanup() clears &fbops->fb_mmap so a per
    		 * instance version is necessary.
    		 */
    		fbops = kzalloc(sizeof(*fbops), GFP_KERNEL);
    		shadow = vzalloc(fbi->screen_size);
    		if (!fbops || !shadow) {
    			kfree(fbops);
    			vfree(shadow);
    			return -ENOMEM;
    		}
    
    		*fbops = *fbi->fbops;
    		fbi->fbops = fbops;
    		fbi->screen_buffer = shadow;
    		fbi->fbdefio = &drm_fbdev_defio;
    
    		fb_deferred_io_init(fbi);
    	} else {
    		/* buffer is mapped for HW framebuffer */
    		vaddr = drm_client_buffer_vmap(fb_helper->buffer);
    		if (IS_ERR(vaddr))
    			return PTR_ERR(vaddr);
    
    		fbi->screen_buffer = vaddr;
    		/* Shamelessly leak the physical address to user-space */
    #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
    		if (drm_leak_fbdev_smem && fbi->fix.smem_start == 0)
    			fbi->fix.smem_start =
    				page_to_phys(virt_to_page(fbi->screen_buffer));
    #endif
    	}
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_generic_probe);
    
    static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
    	.fb_probe = drm_fb_helper_generic_probe,
    };
    
    static void drm_fbdev_client_unregister(struct drm_client_dev *client)
    {
    	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
    
    	if (fb_helper->fbdev)
    		/* drm_fbdev_fb_destroy() takes care of cleanup */
    		drm_fb_helper_unregister_fbi(fb_helper);
    	else
    		drm_fbdev_release(fb_helper);
    }
    
    static int drm_fbdev_client_restore(struct drm_client_dev *client)
    {
    	drm_fb_helper_lastclose(client->dev);
    
    	return 0;
    }
    
    static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
    {
    	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
    	struct drm_device *dev = client->dev;
    	int ret;
    
    	/* Setup is not retried if it has failed */
    	if (!fb_helper->dev && fb_helper->funcs)
    		return 0;
    
    	if (dev->fb_helper)
    		return drm_fb_helper_hotplug_event(dev->fb_helper);
    
    	if (!dev->mode_config.num_connector) {
    		DRM_DEV_DEBUG(dev->dev, "No connectors found, will not create framebuffer!\n");
    		return 0;
    	}
    
    	drm_fb_helper_prepare(dev, fb_helper, &drm_fb_helper_generic_funcs);
    
    	ret = drm_fb_helper_init(dev, fb_helper, 0);
    	if (ret)
    		goto err;
    
    	if (!drm_drv_uses_atomic_modeset(dev))
    		drm_helper_disable_unused_functions(dev);
    
    	ret = drm_fb_helper_initial_config(fb_helper, fb_helper->preferred_bpp);
    	if (ret)
    		goto err_cleanup;
    
    	return 0;
    
    err_cleanup:
    	drm_fbdev_cleanup(fb_helper);
    err:
    	fb_helper->dev = NULL;
    	fb_helper->fbdev = NULL;
    
    	DRM_DEV_ERROR(dev->dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
    
    	return ret;
    }
    
    static const struct drm_client_funcs drm_fbdev_client_funcs = {
    	.owner		= THIS_MODULE,
    	.unregister	= drm_fbdev_client_unregister,
    	.restore	= drm_fbdev_client_restore,
    	.hotplug	= drm_fbdev_client_hotplug,
    };
    
    /**
     * drm_fbdev_generic_setup() - Setup generic fbdev emulation
     * @dev: DRM device
     * @preferred_bpp: Preferred bits per pixel for the device.
     *                 @dev->mode_config.preferred_depth is used if this is zero.
     *
     * This function sets up generic fbdev emulation for drivers that supports
     * dumb buffers with a virtual address and that can be mmap'ed. If the driver
     * does not support these functions, it could use drm_fb_helper_fbdev_setup().
     *
     * Restore, hotplug events and teardown are all taken care of. Drivers that do
     * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
     * Simple drivers might use drm_mode_config_helper_suspend().
     *
     * Drivers that set the dirty callback on their framebuffer will get a shadow
     * fbdev buffer that is blitted onto the real buffer. This is done in order to
     * make deferred I/O work with all kinds of buffers.
     *
     * This function is safe to call even when there are no connectors present.
     * Setup will be retried on the next hotplug event.
     *
     * The fbdev is destroyed by drm_dev_unregister().
     *
     * Returns:
     * Zero on success or negative error code on failure.
     */
    int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
    {
    	struct drm_fb_helper *fb_helper;
    	int ret;
    
    	WARN(dev->fb_helper, "fb_helper is already set!\n");
    
    	if (!drm_fbdev_emulation)
    		return 0;
    
    	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
    	if (!fb_helper)
    		return -ENOMEM;
    
    	ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
    	if (ret) {
    		kfree(fb_helper);
    		DRM_DEV_ERROR(dev->dev, "Failed to register client: %d\n", ret);
    		return ret;
    	}
    
    	if (!preferred_bpp)
    		preferred_bpp = dev->mode_config.preferred_depth;
    	if (!preferred_bpp)
    		preferred_bpp = 32;
    	fb_helper->preferred_bpp = preferred_bpp;
    
    	ret = drm_fbdev_client_hotplug(&fb_helper->client);
    	if (ret)
    		DRM_DEV_DEBUG(dev->dev, "client hotplug ret=%d\n", ret);
    
    	drm_client_register(&fb_helper->client);
    
    	return 0;
    }
    EXPORT_SYMBOL(drm_fbdev_generic_setup);
    
    /* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
     * but the module doesn't depend on any fb console symbols.  At least
     * attempt to load fbcon to avoid leaving the system without a usable console.
     */
    int __init drm_fb_helper_modinit(void)
    {
    #if defined(CONFIG_FRAMEBUFFER_CONSOLE_MODULE) && !defined(CONFIG_EXPERT)
    	const char name[] = "fbcon";
    	struct module *fbcon;
    
    	mutex_lock(&module_mutex);
    	fbcon = find_module(name);
    	mutex_unlock(&module_mutex);
    
    	if (!fbcon)
    		request_module_nowait(name);
    #endif
    	return 0;
    }
    EXPORT_SYMBOL(drm_fb_helper_modinit);