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Subject[PATCH] gpio: core: Do not call get_direction in atomic context for sleeping gpio
Date
When adding the gpiochip, the GPIO HW drivers' callback get_direction()
get called in atomic context. Some of the GPIO HW drivers can sleep when
accessing the register and hence it can create the sleeping call in
atomic context.

Call get_direction() in non-atomic context from gpiochip_add() if GPIO
HW driver is having sleepable callback i.e. chip->can_sleep = 1.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>

---
This is found when implementing the get_direction() of max77620 on 20160520
linux-next.

drivers/gpio/gpiolib.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d407f904..4d04171 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -636,7 +636,15 @@ int gpiochip_add_data(struct gpio_chip *chip, void *data)
* If we have .get_direction, set up the initial
* direction flag from the hardware.
*/
- int dir = chip->get_direction(chip, i);
+ int dir;
+
+ if (chip->can_sleep)
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
+ dir = chip->get_direction(chip, i);
+
+ if (chip->can_sleep)
+ spin_lock_irqsave(&gpio_lock, flags);

if (!dir)
set_bit(FLAG_IS_OUT, &desc->flags);
--
2.1.4
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