diff mbox

[v5,2/2] pwm: core: Set enable state properly on failed call to enable

Message ID 1420659771-31401-3-git-send-email-jonathar@broadcom.com
State Superseded
Headers show

Commit Message

Jonathan Richardson Jan. 7, 2015, 7:42 p.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>
Signed-off-by: Jonathan Richardson <jonathar@broadcom.com>
---
 drivers/pwm/core.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Comments

Dmitry Torokhov Feb. 11, 2015, 11:59 p.m. UTC | #1 
On Wed, Jan 07, 2015 at 11:42:51AM -0800, 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>
> Signed-off-by: Jonathan Richardson <jonathar@broadcom.com>
> ---
>  drivers/pwm/core.c |   10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index f28c4ce..c33e24f 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -477,8 +477,14 @@ 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;
> +
> +	if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
> +		err = pwm->chip->ops->enable(pwm->chip, pwm);
> +		if (err)
> +			clear_bit(PWMF_ENABLED, &pwm->flags);
> +		return err;
> +	}
>  
>  	return pwm ? 0 : -EINVAL;

Seems fine in principle, but somewhat messy. Can we do the following:

int pwm_enable(struct pwm_device *pwm)
{
	int err;

	if (!pwm)
		return -EINVAL;

	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);
			return err;
		}
	}

	return 0;
}

Otherwise:

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks.
diff mbox

Patch

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index f28c4ce..c33e24f 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -477,8 +477,14 @@  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;
+
+	if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
+		err = pwm->chip->ops->enable(pwm->chip, pwm);
+		if (err)
+			clear_bit(PWMF_ENABLED, &pwm->flags);
+		return err;
+	}
 
 	return pwm ? 0 : -EINVAL;
 }