From a2be3931144b8fab73c3d876c148ada7a3c09066 Mon Sep 17 00:00:00 2001
From: Michael Hennerich <michael.hennerich@analog.com>
Date: Wed, 4 Feb 2009 16:49:45 +0800
Subject: [PATCH] Blackfin arch: reset POLAR setting when acquiring a gpio for
the first time
when requesting a GPIO for the first time, the POLAR setting is not
set to a sane state. this can lead to indeterminate behavior that
cannot be resolved without an explicit write to the Blackfin port POLAR
register.
when requesting a GPIO for the first time via gpio_request(), the POLAR
setting for the GPIO in question should be set to sane state. this
should occur if the GPIO has not been allocated in any other way.
some examples:
- when doing something like "request_irq(); gpio_request();" on the
same GPIO, the POLAR setting should not be reset.
- when doing "gpio_request(); gpio_request();" on the same GPIO, the
POLAR setting should be reset only the first time and not the second.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
---
arch/blackfin/kernel/bfin_gpio.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/blackfin/kernel/bfin_gpio.c b/arch/blackfin/kernel/bfin_gpio.c
index ea67ae5b033e4..0c4fc31029c22 100644
--- a/arch/blackfin/kernel/bfin_gpio.c
+++ b/arch/blackfin/kernel/bfin_gpio.c
@@ -1053,9 +1053,15 @@ int bfin_gpio_request(unsigned gpio, const char *label)
local_irq_restore_hw(flags);
return -EBUSY;
}
- if (unlikely(reserved_gpio_irq_map[gpio_bank(gpio)] & gpio_bit(gpio)))
+ if (unlikely(reserved_gpio_irq_map[gpio_bank(gpio)] & gpio_bit(gpio))) {
printk(KERN_NOTICE "bfin-gpio: GPIO %d is already reserved as gpio-irq!"
" (Documentation/blackfin/bfin-gpio-notes.txt)\n", gpio);
+ }
+#ifndef BF548_FAMILY
+ else { /* Reset POLAR setting when acquiring a gpio for the first time */
+ set_gpio_polar(gpio, 0);
+ }
+#endif
reserved_gpio_map[gpio_bank(gpio)] |= gpio_bit(gpio);
set_label(gpio, label);
--
GitLab