This is a note to let you know that I've just added the patch titled
leds: pwm: Don't disable the PWM when the LED should be off
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
leds-pwm-don-t-disable-the-pwm-when-the-led-should-b.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit eb16627b1dc2f1d9cb2ebdb1453e4894e8a02dd1
Author: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Date: Fri Sep 22 21:28:34 2023 +0200
leds: pwm: Don't disable the PWM when the LED should be off
[ Upstream commit 76fe464c8e64e71b2e4af11edeef0e5d85eeb6aa ]
Disabling a PWM (i.e. calling pwm_apply_state with .enabled = false)
gives no guarantees what the PWM output does. It might freeze where it
currently is, or go in a High-Z state or drive the active or inactive
state, it might even continue to toggle.
To ensure that the LED gets really disabled, don't disable the PWM even
when .duty_cycle is zero.
This fixes disabling a leds-pwm LED on i.MX28. The PWM on this SoC is
one of those that freezes its output on disable, so if you disable an
LED that is full on, it stays on. If you disable a LED with half
brightness it goes off in 50% of the cases and full on in the other 50%.
Fixes: 41c42ff5dbe2 ("leds: simple driver for pwm driven LEDs")
Reported-by: Rogan Dawes <rogan@xxxxxxxxxxxx>
Reported-by: Fabio Estevam <festevam@xxxxxxx>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Reviewed-by: Fabio Estevam <festevam@xxxxxxx>
Link: https://lore.kernel.org/r/20230922192834.1695727-1-u.kleine-koenig@xxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index 16c78df7a7632..107e635cac245 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -49,7 +49,7 @@ static int led_pwm_set(struct led_classdev *led_cdev,
duty = led_dat->pwmstate.period - duty;
led_dat->pwmstate.duty_cycle = duty;
- led_dat->pwmstate.enabled = duty > 0;
+ led_dat->pwmstate.enabled = true;
return pwm_apply_state(led_dat->pwm, &led_dat->pwmstate);
}
