Patch "backlight: pwm_bl: Disable PWM on shutdown, suspend and remove" has been added to the 6.5-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    backlight: pwm_bl: Disable PWM on shutdown, suspend and remove

to the 6.5-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:
     backlight-pwm_bl-disable-pwm-on-shutdown-suspend-and.patch
and it can be found in the queue-6.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fce4534c084e6d7fcf024b8edd115856dee9630c
Author: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Date:   Mon Oct 9 11:32:23 2023 +0200

    backlight: pwm_bl: Disable PWM on shutdown, suspend and remove
    
    [ Upstream commit 40da4737717b252fd01d92ff38d3b95a491167cc ]
    
    Since commit 00e7e698bff1 ("backlight: pwm_bl: Configure pwm only once
    per backlight toggle") calling pwm_backlight_power_off() doesn't disable
    the PWM any more. However this is necessary to suspend because PWM
    drivers usually refuse to suspend if they are still enabled.
    
    Also adapt shutdown and remove callbacks to disable the PWM for similar
    reasons.
    
    Fixes: 00e7e698bff1 ("backlight: pwm_bl: Configure pwm only once per backlight toggle")
    Reported-by: Aisheng Dong <aisheng.dong@xxxxxxx>
    Tested-by: Aisheng Dong <aisheng.dong@xxxxxxx>
    Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
    Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20231009093223.227286-1-u.kleine-koenig@xxxxxxxxxxxxxx
    Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index a51fbab963680..289bd9ce4d36d 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -626,9 +626,14 @@ static void pwm_backlight_remove(struct platform_device *pdev)
 {
 	struct backlight_device *bl = platform_get_drvdata(pdev);
 	struct pwm_bl_data *pb = bl_get_data(bl);
+	struct pwm_state state;
 
 	backlight_device_unregister(bl);
 	pwm_backlight_power_off(pb);
+	pwm_get_state(pb->pwm, &state);
+	state.duty_cycle = 0;
+	state.enabled = false;
+	pwm_apply_state(pb->pwm, &state);
 
 	if (pb->exit)
 		pb->exit(&pdev->dev);
@@ -638,8 +643,13 @@ static void pwm_backlight_shutdown(struct platform_device *pdev)
 {
 	struct backlight_device *bl = platform_get_drvdata(pdev);
 	struct pwm_bl_data *pb = bl_get_data(bl);
+	struct pwm_state state;
 
 	pwm_backlight_power_off(pb);
+	pwm_get_state(pb->pwm, &state);
+	state.duty_cycle = 0;
+	state.enabled = false;
+	pwm_apply_state(pb->pwm, &state);
 }
 
 #ifdef CONFIG_PM_SLEEP
@@ -647,12 +657,24 @@ static int pwm_backlight_suspend(struct device *dev)
 {
 	struct backlight_device *bl = dev_get_drvdata(dev);
 	struct pwm_bl_data *pb = bl_get_data(bl);
+	struct pwm_state state;
 
 	if (pb->notify)
 		pb->notify(pb->dev, 0);
 
 	pwm_backlight_power_off(pb);
 
+	/*
+	 * Note that disabling the PWM doesn't guarantee that the output stays
+	 * at its inactive state. However without the PWM disabled, the PWM
+	 * driver refuses to suspend. So disable here even though this might
+	 * enable the backlight on poorly designed boards.
+	 */
+	pwm_get_state(pb->pwm, &state);
+	state.duty_cycle = 0;
+	state.enabled = false;
+	pwm_apply_state(pb->pwm, &state);
+
 	if (pb->notify_after)
 		pb->notify_after(pb->dev, 0);