From d1cd21427747f15920cd726f5f67a07880e7dee4 Mon Sep 17 00:00:00 2001 From: Jonathan Richardson Date: Fri, 16 Oct 2015 17:40:58 -0700 Subject: [PATCH] pwm: Set enable state properly on failed call to enable The pwm_enable() function didn't clear the enabled bit if a call to the driver's ->enable() callback returned an error. The result was that the state of the PWM core was wrong. Clearing the bit when enable returns an error ensures the state is properly set. Tested-by: Jonathan Richardson Reviewed-by: Dmitry Torokhov Signed-off-by: Jonathan Richardson [thierry.reding@gmail.com: add missing kerneldoc for the lock] Signed-off-by: Thierry Reding --- drivers/pwm/core.c | 33 ++++++++++++++++++++++++++------- include/linux/pwm.h | 3 +++ 2 files changed, 29 insertions(+), 7 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 3f9df3ea3350..b8f6c309c160 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -269,6 +269,7 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, pwm->pwm = chip->base + i; pwm->hwpwm = i; pwm->polarity = polarity; + mutex_init(&pwm->lock); radix_tree_insert(&pwm_tree, pwm->pwm, pwm); } @@ -473,16 +474,22 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) if (!pwm->chip->ops->set_polarity) return -ENOSYS; - if (pwm_is_enabled(pwm)) - return -EBUSY; + mutex_lock(&pwm->lock); + + if (pwm_is_enabled(pwm)) { + err = -EBUSY; + goto unlock; + } err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity); if (err) - return err; + goto unlock; pwm->polarity = polarity; - return 0; +unlock: + mutex_unlock(&pwm->lock); + return err; } EXPORT_SYMBOL_GPL(pwm_set_polarity); @@ -494,10 +501,22 @@ EXPORT_SYMBOL_GPL(pwm_set_polarity); */ int pwm_enable(struct pwm_device *pwm) { - if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags)) - return pwm->chip->ops->enable(pwm->chip, pwm); + int err = 0; + + if (!pwm) + return -EINVAL; + + mutex_lock(&pwm->lock); + + if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) { + err = pwm->chip->ops->enable(pwm->chip, pwm); + if (err) + clear_bit(PWMF_ENABLED, &pwm->flags); + } + + mutex_unlock(&pwm->lock); - return pwm ? 0 : -EINVAL; + return err; } EXPORT_SYMBOL_GPL(pwm_enable); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index d681f6875aef..cfc3ed46cad2 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -2,6 +2,7 @@ #define __LINUX_PWM_H #include +#include #include struct pwm_device; @@ -87,6 +88,7 @@ enum { * @pwm: global index of the PWM device * @chip: PWM chip providing this PWM device * @chip_data: chip-private data associated with the PWM device + * @lock: used to serialize accesses to the PWM device where necessary * @period: period of the PWM signal (in nanoseconds) * @duty_cycle: duty cycle of the PWM signal (in nanoseconds) * @polarity: polarity of the PWM signal @@ -98,6 +100,7 @@ struct pwm_device { unsigned int pwm; struct pwm_chip *chip; void *chip_data; + struct mutex lock; unsigned int period; unsigned int duty_cycle; -- 2.20.1