diff mbox

[v10,1/1] pwm: core: Set enable state properly on failed call to enable

Message ID 1445042458-30725-2-git-send-email-jonathar@broadcom.com
State Accepted
Headers show

Commit Message

Jonathan Richardson Oct. 17, 2015, 12:40 a.m. UTC 
The pwm_enable function didn't clear the enabled bit if a call to a
clients enable function 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>
---
 drivers/pwm/core.c  | 33 ++++++++++++++++++++++++++-------
 include/linux/pwm.h |  2 ++
 2 files changed, 28 insertions(+), 7 deletions(-)

Comments

Thierry Reding Nov. 6, 2015, 1:46 p.m. UTC | #1 
On Fri, Oct 16, 2015 at 05:40:58PM -0700, Jonathan Richardson wrote:
> The pwm_enable function didn't clear the enabled bit if a call to a
> clients enable function 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>
> ---
>  drivers/pwm/core.c  | 33 ++++++++++++++++++++++++++-------
>  include/linux/pwm.h |  2 ++
>  2 files changed, 28 insertions(+), 7 deletions(-)

Applied, thanks.

Thierry
diff mbox

Patch

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 3f9df3e..b8f6c30 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 d681f68..dee7d65 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -3,6 +3,7 @@ 
 
 #include <linux/err.h>
 #include <linux/of.h>
+#include <linux/mutex.h>
 
 struct pwm_device;
 struct seq_file;
@@ -98,6 +99,7 @@  struct pwm_device {
 	unsigned int pwm;
 	struct pwm_chip *chip;
 	void *chip_data;
+	struct mutex lock;
 
 	unsigned int period;
 	unsigned int duty_cycle;