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

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 <redacted>
Reviewed-by: Daniel Thompson <redacted>
Cc: <redacted> # 5.4+
Cc: <redacted> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Daniel Thompson <redacted>
Cc: Meghana Madhyastha <redacted>
Cc: Noralf Trønnes <redacted>
Cc: Sean Paul <redacted>
Cc: Thierry Reding <redacted>
---
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

On 7/13/21 9:16 PM, Marek Vasut wrote:

Any news on this ?

Expanding CC list.

On Sat, 11 Sep 2021, Marek Vasut wrote:

On 7/13/21 9:16 PM, Marek Vasut wrote:

quoted

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 <redacted>
Reviewed-by: Daniel Thompson <redacted>
Cc: <redacted> # 5.4+
Cc: <redacted> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Daniel Thompson <redacted>
Cc: Meghana Madhyastha <redacted>
Cc: Noralf Trønnes <redacted>
Cc: Sean Paul <redacted>
Cc: Thierry Reding <redacted>
---
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

On 9/21/21 3:33 PM, Lee Jones wrote:

On Sat, 11 Sep 2021, Marek Vasut wrote:

quoted

On 7/13/21 9:16 PM, Marek Vasut wrote:

quoted

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 <redacted>
Reviewed-by: Daniel Thompson <redacted>
Cc: <redacted> # 5.4+
Cc: <redacted> # 4.19.x: ec665b756e6f7: backlight: gpio-backlight: Correct initial power state handling
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Daniel Thompson <redacted>
Cc: Meghana Madhyastha <redacted>
Cc: Noralf Trønnes <redacted>
Cc: Sean Paul <redacted>
Cc: Thierry Reding <redacted>
---
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/