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

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

[Marek Vasut]

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@tronnes.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: <stable@vger.kernel.org> # 5.4+
Cc: <stable@vger.kernel.org> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Thierry Reding <treding@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;
 		}
 	}
 
-- 
2.30.2

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

[Marek Vasut]

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@tronnes.org>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: <stable@vger.kernel.org> # 5.4+
> Cc: <stable@vger.kernel.org> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> Cc: Noralf Trønnes <noralf@tronnes.org>
> Cc: Sean Paul <seanpaul@chromium.org>
> Cc: Thierry Reding <treding@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.

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

[Lee Jones]

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@tronnes.org>
> > Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> > Cc: <stable@vger.kernel.org> # 5.4+
> > Cc: <stable@vger.kernel.org> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
> > Signed-off-by: Marek Vasut <marex@denx.de>
> > Cc: Daniel Thompson <daniel.thompson@linaro.org>
> > Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> > Cc: Noralf Trønnes <noralf@tronnes.org>
> > Cc: Sean Paul <seanpaul@chromium.org>
> > Cc: Thierry Reding <treding@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.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [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@tronnes.org>
>>> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
>>> Cc: <stable@vger.kernel.org> # 5.4+
>>> Cc: <stable@vger.kernel.org> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
>>> Signed-off-by: Marek Vasut <marex@denx.de>
>>> Cc: Daniel Thompson <daniel.thompson@linaro.org>
>>> Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com>
>>> Cc: Noralf Trønnes <noralf@tronnes.org>
>>> Cc: Sean Paul <seanpaul@chromium.org>
>>> Cc: Thierry Reding <treding@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/