[PATCH V2] video: backlight: Drop maximum brightness override for brightness zero

[Marek Vasut]

On 9/21/21 3:33 PM, Lee Jones wrote:
> On Sat, 11 Sep 2021, Marek Vasut wrote:
> 
>> On 7/13/21 9:16 PM, Marek Vasut wrote:
>>> The note in c2adda27d202f ("video: backlight: Add of_find_backlight helper
>>> in backlight.c") says that gpio-backlight uses brightness as power state.
>>> This has been fixed since in ec665b756e6f7 ("backlight: gpio-backlight:
>>> Correct initial power state handling") and other backlight drivers do not
>>> require this workaround. Drop the workaround.
>>>
>>> This fixes the case where e.g. pwm-backlight can perfectly well be set to
>>> brightness 0 on boot in DT, which without this patch leads to the display
>>> brightness to be max instead of off.
>>>
>>> Fixes: c2adda27d202f ("video: backlight: Add of_find_backlight helper in backlight.c")
>>> Acked-by: Noralf Trønnes <noralf at tronnes.org>
>>> Reviewed-by: Daniel Thompson <daniel.thompson at linaro.org>
>>> Cc: <stable at vger.kernel.org> # 5.4+
>>> Cc: <stable at vger.kernel.org> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
>>> Signed-off-by: Marek Vasut <marex at denx.de>
>>> Cc: Daniel Thompson <daniel.thompson at linaro.org>
>>> Cc: Meghana Madhyastha <meghana.madhyastha at gmail.com>
>>> Cc: Noralf Trønnes <noralf at tronnes.org>
>>> Cc: Sean Paul <seanpaul at chromium.org>
>>> Cc: Thierry Reding <treding at nvidia.com>
>>> ---
>>> V2: Add AB/RB, CC stable
>>> ---
>>>    drivers/video/backlight/backlight.c | 6 ------
>>>    1 file changed, 6 deletions(-)
>>>
>>> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
>>> index 537fe1b376ad7..fc990e576340b 100644
>>> --- a/drivers/video/backlight/backlight.c
>>> +++ b/drivers/video/backlight/backlight.c
>>> @@ -688,12 +688,6 @@ static struct backlight_device *of_find_backlight(struct device *dev)
>>>    			of_node_put(np);
>>>    			if (!bd)
>>>    				return ERR_PTR(-EPROBE_DEFER);
>>> -			/*
>>> -			 * Note: gpio_backlight uses brightness as
>>> -			 * power state during probe
>>> -			 */
>>> -			if (!bd->props.brightness)
>>> -				bd->props.brightness = bd->props.max_brightness;
>>>    		}
>>>    	}
>>>
>>
>> Any news on this ?
>>
>> Expanding CC list.
> 
> Looks like I was left off of the original submission.
> 
> I can't apply a quoted patch.  Please re-submit.

I see. It seems the patch is available in both Lore and Patchwork:

https://lore.kernel.org/all/072e01b7-8554-de4f-046a-da11af3958d6@denx.de/T/

https://patchwork.freedesktop.org/patch/443823/