[PATCH AUTOSEL for 4.9 28/52] led: core: Fix brightness setting when setting delay_off=0

[PATCH AUTOSEL for 4.9 28/52] led: core: Fix brightness setting when setting delay_off=0

[Sasha Levin]

From: Matthieu CASTET <matthieu.castet@parrot.com>

[ Upstream commit 2b83ff96f51d0b039c4561b9f95c824d7bddb85c ]

With the current code, the following sequence won't work :
echo timer > trigger

echo 0 >  delay_off
* at this point we call
** led_delay_off_store
** led_blink_set
*** stop timer
** led_blink_setup
** led_set_software_blink
*** if !delay_on, led off
*** if !delay_off, set led_set_brightness_nosleep <--- LED_BLINK_SW is set but timer is stop
*** otherwise start timer/set LED_BLINK_SW flag

echo xxx > brightness
* led_set_brightness
** if LED_BLINK_SW
*** if brightness=0, led off
*** else apply brightness if next timer <--- timer is stop, and will never apply new setting
** otherwise set led_set_brightness_nosleep

To fix that, when we delete the timer, we should clear LED_BLINK_SW.

Cc: linux-leds@vger.kernel.org
Signed-off-by: Matthieu CASTET <matthieu.castet@parrot.com>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/leds/led-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 3bce44893021..d70d4a5273b8 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -186,7 +186,7 @@ void led_blink_set(struct led_classdev *led_cdev,
 		   unsigned long *delay_on,
 		   unsigned long *delay_off)
 {
-	del_timer_sync(&led_cdev->blink_timer);
+	led_stop_software_blink(led_cdev);
 
 	led_cdev->flags &= ~LED_BLINK_ONESHOT;
 	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
-- 
2.11.0

Re: [PATCH AUTOSEL for 4.9 28/52] led: core: Fix brightness setting when setting delay_off=0

[Jacek Anaszewski]

Hi Sasha,

All 3.18, 4.4 and 4.9 also require the follow-up
patch [0], similarly like autosel did it for 4.14,
since this one alone breaks the other use case.

[0] https://lkml.org/lkml/2018/2/3/249

On 02/03/2018 07:03 PM, Sasha Levin wrote:
> From: Matthieu CASTET <matthieu.castet@parrot.com>
> 
> [ Upstream commit 2b83ff96f51d0b039c4561b9f95c824d7bddb85c ]
> 
> With the current code, the following sequence won't work :
> echo timer > trigger
> 
> echo 0 >  delay_off
> * at this point we call
> ** led_delay_off_store
> ** led_blink_set
> *** stop timer
> ** led_blink_setup
> ** led_set_software_blink
> *** if !delay_on, led off
> *** if !delay_off, set led_set_brightness_nosleep <--- LED_BLINK_SW is set but timer is stop
> *** otherwise start timer/set LED_BLINK_SW flag
> 
> echo xxx > brightness
> * led_set_brightness
> ** if LED_BLINK_SW
> *** if brightness=0, led off
> *** else apply brightness if next timer <--- timer is stop, and will never apply new setting
> ** otherwise set led_set_brightness_nosleep
> 
> To fix that, when we delete the timer, we should clear LED_BLINK_SW.
> 
> Cc: linux-leds@vger.kernel.org
> Signed-off-by: Matthieu CASTET <matthieu.castet@parrot.com>
> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
> ---
>  drivers/leds/led-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 3bce44893021..d70d4a5273b8 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -186,7 +186,7 @@ void led_blink_set(struct led_classdev *led_cdev,
>  		   unsigned long *delay_on,
>  		   unsigned long *delay_off)
>  {
> -	del_timer_sync(&led_cdev->blink_timer);
> +	led_stop_software_blink(led_cdev);
>  
>  	led_cdev->flags &= ~LED_BLINK_ONESHOT;
>  	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
> 

-- 
Best regards,
Jacek Anaszewski

Re: [PATCH AUTOSEL for 4.9 28/52] led: core: Fix brightness setting when setting delay_off=0

[Jacek Anaszewski]

On 02/03/2018 10:22 PM, Jacek Anaszewski wrote:
> Hi Sasha,
> 
> All 3.18, 4.4 and 4.9 also require the follow-up
> patch [0], similarly like autosel did it for 4.14,
> since this one alone breaks the other use case.

Actually after taking closer look, it turns out that
the patch [0] applies cleanly only to 4.14.

4.9 requires also the patch :

eb1610b4c273 ("led: core: Fix blink_brightness setting race")

3.18 and 4.4 shouldn't have the issue since it was introduced
along with LED_BLINK_SW flag added in 4.7.

Thanks,
Jacek Anaszewski

> [0] https://lkml.org/lkml/2018/2/3/249
> 
> On 02/03/2018 07:03 PM, Sasha Levin wrote:
>> From: Matthieu CASTET <matthieu.castet@parrot.com>
>>
>> [ Upstream commit 2b83ff96f51d0b039c4561b9f95c824d7bddb85c ]
>>
>> With the current code, the following sequence won't work :
>> echo timer > trigger
>>
>> echo 0 >  delay_off
>> * at this point we call
>> ** led_delay_off_store
>> ** led_blink_set
>> *** stop timer
>> ** led_blink_setup
>> ** led_set_software_blink
>> *** if !delay_on, led off
>> *** if !delay_off, set led_set_brightness_nosleep <--- LED_BLINK_SW is set but timer is stop
>> *** otherwise start timer/set LED_BLINK_SW flag
>>
>> echo xxx > brightness
>> * led_set_brightness
>> ** if LED_BLINK_SW
>> *** if brightness=0, led off
>> *** else apply brightness if next timer <--- timer is stop, and will never apply new setting
>> ** otherwise set led_set_brightness_nosleep
>>
>> To fix that, when we delete the timer, we should clear LED_BLINK_SW.
>>
>> Cc: linux-leds@vger.kernel.org
>> Signed-off-by: Matthieu CASTET <matthieu.castet@parrot.com>
>> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
>> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
>> ---
>>  drivers/leds/led-core.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
>> index 3bce44893021..d70d4a5273b8 100644
>> --- a/drivers/leds/led-core.c
>> +++ b/drivers/leds/led-core.c
>> @@ -186,7 +186,7 @@ void led_blink_set(struct led_classdev *led_cdev,
>>  		   unsigned long *delay_on,
>>  		   unsigned long *delay_off)
>>  {
>> -	del_timer_sync(&led_cdev->blink_timer);
>> +	led_stop_software_blink(led_cdev);
>>  
>>  	led_cdev->flags &= ~LED_BLINK_ONESHOT;
>>  	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
>>
>