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pwm: Make it explicit that pwm_apply_state() might sleep

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At least some implementations sleep. So mark pwm_apply_state() with a
might_sleep() to make callers aware. In the worst case this uncovers a
valid atomic user, then we revert this patch and at least gained some more
knowledge and then can work on a concept similar to
gpio_get_value/gpio_get_value_cansleep.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Uwe Kleine-König 2021-09-09 11:48:49 +02:00 committed by Thierry Reding
parent 27d9a4d694
commit 4ad91a2278
2 changed files with 13 additions and 0 deletions
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9
drivers/pwm/core.c
View File

@ -532,6 +532,15 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
struct pwm_chip *chip;
int err;
/*
* Some lowlevel driver's implementations of .apply() make use of
* mutexes, also with some drivers only returning when the new
* configuration is active calling pwm_apply_state() from atomic context
* is a bad idea. So make it explicit that calling this function might
* sleep.
*/
might_sleep();
if (!pwm || !state || !state->period ||
state->duty_cycle > state->period)
return -EINVAL;

4
include/linux/pwm.h
View File

@ -441,6 +441,7 @@ static inline void pwm_free(struct pwm_device *pwm)
static inline int pwm_apply_state(struct pwm_device *pwm,
const struct pwm_state *state)
{
might_sleep();
return -ENOTSUPP;
}
@ -452,6 +453,7 @@ static inline int pwm_adjust_config(struct pwm_device *pwm)
static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
int period_ns)
{
might_sleep();
return -EINVAL;
}
@ -464,11 +466,13 @@ static inline int pwm_capture(struct pwm_device *pwm,
static inline int pwm_enable(struct pwm_device *pwm)
{
might_sleep();
return -EINVAL;
}
static inline void pwm_disable(struct pwm_device *pwm)
{
might_sleep();
}
static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)