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Message-ID: <20240417153846.271751-2-u.kleine-koenig@pengutronix.de>
Date: Wed, 17 Apr 2024 17:38:47 +0200
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: Lee Jones <lee@...nel.org>
Cc: Linux regressions mailing list <regressions@...ts.linux.dev>,
linux-leds@...r.kernel.org,
linux-pwm@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>,
kernel@...gutronix.de
Subject: [PATCH] leds: pwm: Disable PWM when going to suspend
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@...gutronix.de>
---
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
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