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authorJonathan Richardson <jonathar@broadcom.com>2015-10-17 03:40:58 +0300
committerThierry Reding <thierry.reding@gmail.com>2015-11-10 15:06:16 +0300
commitd1cd21427747f15920cd726f5f67a07880e7dee4 (patch)
tree429e8844a75def440f47479f751e60f9ff685f0c
parentf080be27d7d9333e4815655a2cedab91c3aa7acc (diff)
downloadlinux-d1cd21427747f15920cd726f5f67a07880e7dee4.tar.xz
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 <jonathar@broadcom.com> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Jonathan Richardson <jonathar@broadcom.com> [thierry.reding@gmail.com: add missing kerneldoc for the lock] Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
-rw-r--r--drivers/pwm/core.c33
-rw-r--r--include/linux/pwm.h3
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 <linux/err.h>
+#include <linux/mutex.h>
#include <linux/of.h>
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;