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

Lewis Toohey
2014-05-23T12:40:30Z

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.

I copied and pasted that text into a file in my home directory and
called it "backlight.diff". When I ran "patch < backlight.diff" it
complains that it cannot find the file to patch. I am not familiar
with the syntax of a patch file so I can't work out what's going
wrong.

I thought that the diff file might need to be placed relative to the
path referred to within it but "locate nouveau_backlight.c" returns no
results so I don't know where to put it.

Can you advise?

Very grateful for your continued help and patience