[RESEND][PATCH v2] video: backlight: Drop maximum brightness override for brightness zero

[RESEND][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: Lee Jones <lee.jones@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;
 		}
 	}
 
-- 
2.33.0

Re: [RESEND][PATCH v2] video: backlight: Drop maximum brightness override for brightness zero

[Lee Jones]

On Tue, 21 Sep 2021, 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: Lee Jones <lee.jones@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(-)

Applied with some changes to the sign-off block, thanks.

> 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;
>  		}
>  	}
>  

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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