[PATCH] leds: pwm: Disable PWM when going to suspend

From: Uwe Kleine-König
Date: Wed Apr 17 2024 - 11:41:19 EST


On stm32mp1xx based machines (and others) a PWM consumer has to disable
the PWM because an enabled PWM refuses to suspend. So check the
LED_SUSPENDED flag and depending on that set the .enabled property.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=218559
Fixes: 76fe464c8e64 ("leds: pwm: Don't disable the PWM when the LED should be off")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
---
Hello,

On Wed, Apr 17, 2024 at 03:49:43PM +0100, Lee Jones wrote:
> On Tue, 16 Apr 2024, Uwe Kleine-König wrote:
> > If you don't consider that suitable, I can create a patch that is easier
> > to pick up.
>
> Yes, please submit it properly.

Here it comes.

Best regards
Uwe

drivers/leds/leds-pwm.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index 4e3936a39d0e..e1b414b40353 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -53,7 +53,13 @@ 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 = true;
+ /*
+ * Disabling a PWM doesn't guarantee that it emits the inactive level.
+ * So keep it on. Only for suspending the PWM should be disabled because
+ * otherwise it refuses to suspend. The possible downside is that the
+ * LED might stay (or even go) on.
+ */
+ led_dat->pwmstate.enabled = !(led_cdev->flags & LED_SUSPENDED);
return pwm_apply_might_sleep(led_dat->pwm, &led_dat->pwmstate);
}


base-commit: 4eab358930711bbeb85bf5ee267d0d42d3394c2c
--
2.43.0