Re: Bug Report - [Acer Aspire V5-122P] Unable to adjust screen brightness

[Aaron Lu <aaron.lu@intel.com>]

On 05/27/2014 03:09 AM, Lewis Toohey wrote:
> On 26 May 2014 13:18, Lewis Toohey <lewis@toohey.co.uk> wrote:
>> On 26 May 2014 06:48, Aaron Lu <aaron.lu@intel.com> wrote:
>>> On 05/26/2014 04:42 AM, Lewis Toohey wrote:
>>>> On 23 May 2014 13:50, Hans de Goede <hdegoede@redhat.com> wrote:
>>>>> Hi Lewis et all,
>>>>>
>>>>> On 05/23/2014 02:07 PM, Lewis Toohey wrote:
>>>>>> On 23 May 2014 02:34, Aaron Lu <aaron.lu@intel.com> wrote:
>>>>>>> On 05/21/2014 09:02 PM, Lewis Toohey wrote:
>>>>>>>> Hi Aaron
>>>>>>>>
>>>>>>>> I followed your instructions and can report some limited success. I
>>>>>>>> have two interfaces listed in /sys/class/backlight namely:
>>>>>>>>   acpi_video0  radeon_bl0
>>>>>>>>
>>>>>>>> max_brightness for acpi_video0 is 11. Echo-ing new values to
>>>>>>>> brightness appears to have no effect.
>>>>>>>>
>>>>>>>> max_brightness for radeon_bl0 is 255. Echo-ing new values to
>>>>>>>> brightness does adjust the screen brightness as you would expect.
>>>>>>>>
>>>>>>>> Results are the same on both battery and powered.
>>>>>>>>
>>>>>>>> I hope that is useful.
>>>>>>>
>>>>>>> I think Hans' patchset should solve your problem, can you please give it
>>>>>>> a try? You will need to pass the video.use_native_backlight=1 to kernel
>>>>>>> cmdline when testing, thanks.
>>>>>>>
>>>>>>> [PATCH resend 0/4] Make video.use_native_backlight=1 work properly with nouveau
>>>>>>> http://www.spinics.net/lists/dri-devel/msg59941.html
>>>>>>>
>>>>>>> -Aaron
>>>>>>
>>>>>> Aaron
>>>>>>
>>>>>> Thank you for this. Unfortunately I am going to have to ask you for a
>>>>>> bit of help here as I am now, officially, "out of my depth". I
>>>>>> appreciate this is a pain as you will have to take time explaining it
>>>>>> to me and I apologise for that.
>>>>>>
>>>>>> I have figured out how to pass the kernel command line argument, this
>>>>>> is not an issue.
>>>>>>
>>>>>> I have located the patch you refer to here:
>>>>>> https://bugzilla.redhat.com/attachment.cgi?id=894577
>>>>>> (which I believe is correct) but I cannot figure out how to apply it.
>>>>>
>>>>> That is not the right patch, you need a set of 2 patches. I've attached
>>>>> them to this mail. Note please ignore the numbering starting at 6, these
>>>>> are the 2 patches you need. You will need to build a Linux kernel with
>>>>> these 2 patches applied, see your distributions documentation on how
>>>>> to build a kernel from source.
>>>>>
>>>>> I don't know which distro you are using, I've a Fedora kernel with this
>>>>> patches included available here:
>>>>>
>>>>> http://people.fedoraproject.org/~jwrdegoede/rhbz1093171/
>>>>>
>>>>> Regards,
>>>>>
>>>>> Hans
>>>>
>>>> Hans
>>>>
>>>> Unfortunately I am unable to apply these patches against the latest
>>>> mainline kernel. I get two fails when applying the second patch file
>>>> and then the kernel will not compile. Please see output information
>>>> below.
>>>
>>> I've prepared a git branch for you:
>>> https://github.com/aaronlu/linux.git for-lewis
>>>
>>> It's based on Rafael's linux-next plus Hans' patch 2 and 3.
>>>
>>> Thanks,
>>> Aaron
>>>
>>>>
>>>> Can you advise?
>>>>
>>>> Many thanks
>>>>
>>>> ===APPLYING PATCHES TO LATEST MAINLINE KERNEL====
>>>>
>>>> lewis@HappyFunMeaowMeaow:~/KernelTesting/Kernel/linux$ patch -p1 <
>>>> 0006-backlight-Add-backlight-device-un-registration-notif.patch
>>>> (Stripping trailing CRs from patch; use --binary to disable.)
>>>> patching file drivers/video/backlight/backlight.c
>>>> (Stripping trailing CRs from patch; use --binary to disable.)
>>>> patching file include/linux/backlight.h
>>>> lewis@HappyFunMeaowMeaow:~/KernelTesting/Kernel/linux$ patch -p1 <
>>>> 0007-acpi-video-Unregister-the-backlight-device-if-a-raw-.patch
>>>> (Stripping trailing CRs from patch; use --binary to disable.)
>>>> patching file drivers/acpi/video.c
>>>> Hunk #1 FAILED at 151.
>>>> Hunk #2 succeeded at 161 (offset -1 lines).
>>>> Hunk #3 FAILED at 1837.
>>>> Hunk #4 succeeded at 1868 (offset -113 lines).
>>>> Hunk #5 succeeded at 1999 (offset -113 lines).
>>>> Hunk #6 succeeded at 2023 (offset -113 lines).
>>>> 2 out of 6 hunks FAILED -- saving rejects to file drivers/acpi/video.c.rej
>>>>
>>>>
>>>> ==LAST LINES OF BUILD BEFORE FAIL===
>>>>
>>>>   CC [M]  fs/xfs/xfs_ioctl32.o
>>>>   LD [M]  fs/xfs/xfs.o
>>>> make[1]: Leaving directory `/home/lewis/KernelTesting/Kernel/linux'
>>>> make: *** [debian/stamp/build/kernel] Error 2
>>>> lewis@HappyFunMeaowMeaow:~/KernelTesting/Kernel/linux$
>>>>
>>>>
>>>
>>
>> Aaron
>>
>> Many thanks for this. I can confirm that booting with this kernel and
>> passing the video.use_native_backlight = 1 argument means that the
>> backlight works perfectly on my laptop (both using the keyboard hot
>> keys and the gnome/unity settings applet).
>>
>> I'll post to the ubuntu launchpad page later with instructions for
>> other people to do this. I assume its presence in the linux-next tree
>> means that it will be fixed in an upcoming kernel release? (sorry, I
>> don't know quite how the process works).
>>
>> If I can provide more information or do some more useful testing
>> please do not hesitate to let me know.
>>
>> Thank you both for your help - really appreciated.
>>
>> --
>> Lewis
>>
> 
> Aaron
> 
> Just one final point in case it is relevant / useful - although it
> fixes the backlight issue this kernel version breaks the suspend
> resume functionality for me (the system will suspend but cannot come
> back from it).

That sounds like a regression somewhere and a git bisect would be great
if that's possible for you.

Thanks,
Aaron

> 
> Not asking for a fix (appreciate it is a testing base), just thought
> it might be useful to know.
> 
> Thanks again
> 
>