[PATCH] pwm: lpss: Remove ->free() callback

[PATCH] pwm: lpss: Remove ->free() callback

[Mika Westerberg]

The LPSS PWM driver calls pwm_lpss_disable() when the PWM device is
released (for example unexported from sysfs). This in turn calls
pm_runtime_put() which makes runtime PM count to be unbalanced if the
device has not been enabled at this point.

This is easy to reproduce:

  # cd /sys/class/pwm/pwmchip0
  # echo 0 > export
  # echo 0 > unexport

The count is unbalanced and prevents the PWM device from being powered on
next time.

Fix this by removing ->free() callback. There are no resources to be
released anyway.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/pwm/pwm-lpss.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 6063c3dcbd46..ba9f17443843 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -159,7 +159,6 @@ static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 }
 
 static const struct pwm_ops pwm_lpss_ops = {
-	.free = pwm_lpss_disable,
 	.config = pwm_lpss_config,
 	.enable = pwm_lpss_enable,
 	.disable = pwm_lpss_disable,
-- 
2.6.2

Re: [PATCH] pwm: lpss: Remove ->free() callback

[Thierry Reding]

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On Wed, Dec 09, 2015 at 04:05:59PM +0200, Mika Westerberg wrote:
> The LPSS PWM driver calls pwm_lpss_disable() when the PWM device is
> released (for example unexported from sysfs). This in turn calls
> pm_runtime_put() which makes runtime PM count to be unbalanced if the
> device has not been enabled at this point.
> 
> This is easy to reproduce:
> 
>   # cd /sys/class/pwm/pwmchip0
>   # echo 0 > export
>   # echo 0 > unexport
> 
> The count is unbalanced and prevents the PWM device from being powered on
> next time.
> 
> Fix this by removing ->free() callback. There are no resources to be
> released anyway.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
>  drivers/pwm/pwm-lpss.c | 1 -
>  1 file changed, 1 deletion(-)

Applied, thanks.

Thierry

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