Commit 9b7530cc authored by Linus Torvalds's avatar Linus Torvalds

i915: cleanup coding horrors in i915_gem_gtt_pwrite()

Yes, this will probably be switched over to a cleaner model anyway, but
in the meantime I don't want to see the 'unused variable' warnings that
come from the disgusting #ifdef code.  Make the special case be a nice
inlien function of its own, clean up the code, and make the warning go
away.

I wish people didn't write code that gets (valid) warnings from the
compiler, but I'll limit my fixes to code that I actually care about (in
this case just because I see the warning and it annoys me).
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1ae87786
......@@ -171,6 +171,36 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
return 0;
}
/*
* Try to write quickly with an atomic kmap. Return true on success.
*
* If this fails (which includes a partial write), we'll redo the whole
* thing with the slow version.
*
* This is a workaround for the low performance of iounmap (approximate
* 10% cpu cost on normal 3D workloads). kmap_atomic on HIGHMEM kernels
* happens to let us map card memory without taking IPIs. When the vmap
* rework lands we should be able to dump this hack.
*/
static inline int fast_user_write(unsigned long pfn, char __user *user_data, int l)
{
#ifdef CONFIG_HIGHMEM
unsigned long unwritten;
char *vaddr_atomic;
vaddr_atomic = kmap_atomic_pfn(pfn, KM_USER0);
#if WATCH_PWRITE
DRM_INFO("pwrite i %d o %d l %d pfn %ld vaddr %p\n",
i, o, l, pfn, vaddr_atomic);
#endif
unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + o, user_data, l);
kunmap_atomic(vaddr_atomic, KM_USER0);
return !unwritten;
#else
return 0;
#endif
}
static int
i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
struct drm_i915_gem_pwrite *args,
......@@ -180,12 +210,7 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
ssize_t remain;
loff_t offset;
char __user *user_data;
char __iomem *vaddr;
char *vaddr_atomic;
int i, o, l;
int ret = 0;
unsigned long pfn;
unsigned long unwritten;
user_data = (char __user *) (uintptr_t) args->data_ptr;
remain = args->size;
......@@ -209,6 +234,9 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
obj_priv->dirty = 1;
while (remain > 0) {
unsigned long pfn;
int i, o, l;
/* Operation in this page
*
* i = page number
......@@ -223,25 +251,10 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
pfn = (dev->agp->base >> PAGE_SHIFT) + i;
#ifdef CONFIG_HIGHMEM
/* This is a workaround for the low performance of iounmap
* (approximate 10% cpu cost on normal 3D workloads).
* kmap_atomic on HIGHMEM kernels happens to let us map card
* memory without taking IPIs. When the vmap rework lands
* we should be able to dump this hack.
*/
vaddr_atomic = kmap_atomic_pfn(pfn, KM_USER0);
#if WATCH_PWRITE
DRM_INFO("pwrite i %d o %d l %d pfn %ld vaddr %p\n",
i, o, l, pfn, vaddr_atomic);
#endif
unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + o,
user_data, l);
kunmap_atomic(vaddr_atomic, KM_USER0);
if (!fast_user_write(pfn, user_data, l)) {
unsigned long unwritten;
char __iomem *vaddr;
if (unwritten)
#endif /* CONFIG_HIGHMEM */
{
vaddr = ioremap_wc(pfn << PAGE_SHIFT, PAGE_SIZE);
#if WATCH_PWRITE
DRM_INFO("pwrite slow i %d o %d l %d "
......
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