[patch for 2.6.34? 1/1] acpi: video: fix acpi_backlight=video

[patch for 2.6.34? 1/1] acpi: video: fix acpi_backlight=video

[akpm]

From: Kamal Mostafa <kamal@canonical.com>

Make "acpi_backlight=video" param enable ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO
as intended, instead of incorrectly enabling video output switching.

Addresses http://bugs.launchpad.net/bugs/573120

Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/acpi/video_detect.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN drivers/acpi/video_detect.c~acpi-video-fix-acpi_backlight=video drivers/acpi/video_detect.c
--- a/drivers/acpi/video_detect.c~acpi-video-fix-acpi_backlight=video
+++ a/drivers/acpi/video_detect.c
@@ -250,7 +250,7 @@ static int __init acpi_backlight(char *s
 				ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
 		if (!strcmp("video", str))
 			acpi_video_support |=
-				ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO;
+				ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
 	}
 	return 1;
 }
_

Re: [patch for 2.6.34? 1/1] acpi: video: fix acpi_backlight=video

[Thomas Renninger]

On Thursday 13 May 2010 00:33:57 akpm@linux-foundation.org wrote:
> From: Kamal Mostafa <kamal@canonical.com>
> 
> Make "acpi_backlight=video" param enable
> ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO
> as intended, instead of incorrectly enabling video output switching.

This one is correct and absolutely safe.

Signed-off-by: Thomas Renninger <trenn@suse.de>

      Thomas

Re: [patch for 2.6.34? 1/1] acpi: video: fix acpi_backlight=video

[Thomas Renninger]

On Thursday 13 May 2010 12:33:57 am akpm@linux-foundation.org wrote:
> From: Kamal Mostafa <kamal@canonical.com>
>
> Make "acpi_backlight=video" param enable ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO
> as intended, instead of incorrectly enabling video output switching.
IIRC the only native driver which takes over backlight switching is panasonic,
because Len saw 2 brightness steps missing.
This one should have been solved by a "compatibility" patch from Rui and
this one could also use video.ko by default.

Still, this one is a safe fix.
Just in case someone wants to avoid the use of this boot param and get
things done right by default (and likes to send a patch for it :)).

      Thomas

> Addresses http://bugs.launchpad.net/bugs/573120
>
> Signed-off-by: Kamal Mostafa <kamal@canonical.com>
> Cc: Len Brown <lenb@kernel.org>
> Cc: Zhang Rui <rui.zhang@intel.com>
> Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
> Cc: Jiri Kosina <jkosina@suse.cz>
> Cc: <stable@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
>  drivers/acpi/video_detect.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff -puN drivers/acpi/video_detect.c~acpi-video-fix-acpi_backlight=video
> drivers/acpi/video_detect.c ---
> a/drivers/acpi/video_detect.c~acpi-video-fix-acpi_backlight=video +++
> a/drivers/acpi/video_detect.c
> @@ -250,7 +250,7 @@ static int __init acpi_backlight(char *s
>  				ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
>  		if (!strcmp("video", str))
>  			acpi_video_support |=
> -				ACPI_VIDEO_OUTPUT_SWITCHING_FORCE_VIDEO;
> +				ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
>  	}
>  	return 1;
>  }
> _
> --
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