Re: 2.6.38-rc2: acpi backlight control missing

[Thomas Meyer]

Am 31.01.2011 um 21:39 schrieb "Rafael J. Wysocki" <rjw@xxxxxxx>:

> On Friday, January 28, 2011, Thomas Meyer wrote:
>> Am Samstag, den 22.01.2011, 20:43 +0100 schrieb Rafael J. Wysocki:
>>> On Saturday, January 22, 2011, Thomas Meyer wrote:
>>>> with 2.6.38-rc2 the acpi backlight is gone:
>>>> 
>>>> any ideas?
>>> 
>>> Not really, but Matthew may have some (CCed).
>> 
>> Okay, found the problem.
>> 
>> This commit broke my backlight:
>> 
>> commit 677bd810eedce61edf15452491781ff046b92edc
>> Author: Zhang Rui <rui.zhang@xxxxxxxxx>
>> Date:   Mon Dec 6 15:04:21 2010 +0800
>> 
>>    ACPI video: remove output switching control
>> 
>> This is because in function
>> "acpi_is_video_device()" (drivers/acpi/video_detect.c) the backlight
>> device is only checked when some video capabilities were found, but by
>> removing the check for the VIDEO_OUTPUT_SWITCHING (that seems to be the
>> only video capability on my system) the check for the backlight device
>> isn't done anymore.
>> 
>> by reverting above commit, the backlight is back again.
> 
> Is it the same issue as https://bugzilla.kernel.org/show_bug.cgi?id=27702 ?

Yes, it is.

> In case it is, can you test the patch in there, please?
> 

Didn't test the patch. But it should do the trick.

> Rafael
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