linux-kernel - [PATCH] leds: pwm-multicolor: Disable PWM when going to suspend

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Message-ID: <d7d930bc-4c82-4272-b2c6-88f7cac5a3e1@chaosfield.at>
Date: Mon, 2 Dec 2024 10:33:54 +0100
From: Jakob Riepler <jakob+lkml@...osfield.at>
To: Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>
Cc: linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Subject: [PATCH] leds: pwm-multicolor: Disable PWM when going to suspend

This fixes suspend on platforms like stm32mp1xx, where the PWM consumer
has to be disabled for the PWM to enter suspend.
Another positive side effect is that active-low LEDs now properly
turn off instead of going back to full brightness when they are set to 0.

Link: 
https://lore.kernel.org/all/20240417153846.271751-2-u.kleine-koenig@pengutronix.de/
Signed-off-by: Jakob Riepler <jakob+lkml@...osfield.at>
---
  drivers/leds/rgb/leds-pwm-multicolor.c | 8 +++++++-
  1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/rgb/leds-pwm-multicolor.c 
b/drivers/leds/rgb/leds-pwm-multicolor.c
index e1a81e0109e8..f80a06cc31f8 100644
--- a/drivers/leds/rgb/leds-pwm-multicolor.c
+++ b/drivers/leds/rgb/leds-pwm-multicolor.c
@@ -50,7 +50,13 @@ static int led_pwm_mc_set(struct led_classdev *cdev,
              duty = priv->leds[i].state.period - duty;

          priv->leds[i].state.duty_cycle = duty;
-        priv->leds[i].state.enabled = duty > 0;
+        /*
+         * 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.
+         */
+        priv->leds[i].state.enabled = !(cdev->flags & LED_SUSPENDED);
          ret = pwm_apply_might_sleep(priv->leds[i].pwm,
                          &priv->leds[i].state);
          if (ret)
-- 
2.47.0