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: 76fe464c ("leds: pwm: Don't disable the PWM when the LED should be off")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20240417153846.271751-2-u.kleine-koenig@pengutronix.deSigned-off-by: Lee Jones <lee@kernel.org>

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);
 }