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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>
This commit is contained in:
Michael Hennerich 2009-02-04 16:49:45 +08:00 committed by Bryan Wu
parent 5e7bb132bb
commit a2be393114
1 changed files with 7 additions and 1 deletions
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8
arch/blackfin/kernel/bfin_gpio.c
View File

@ -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);