Re: [Bug 105051] Radeon sets max_brightness to -1, breaking GNOME backlight control on Macbook Pro mid-2015 11,5

[Darren Hart <dvhart@infradead.org>]

Bruno, can you please have a look at the following regression attributed to:

4eebd5a apple-gmux: lock iGP IO to protect from vgaarb changes
 2015-03-18 (7 months ago), Bruno Prémont <bonbons@linux-vserver.org>


On Thu, Oct 15, 2015 at 04:47:13AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=105051
> 
> Felipe Ortiz <fortizc@gmail.com> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                            |fortizc@gmail.com
> 
> --- Comment #14 from Felipe Ortiz <fortizc@gmail.com> ---
> I can confirm the problem with 4eebd5a4e72697aac25a8a57d3f888a9d5f80370. I have
> a MPB 11,5 with AMD/Intel graphics. I recompile the module (a previous version
> of 4eebd5a4e72697aac25a8a57d3f888a9d5f80370) and brightness adjusts is working
> again.
> 
> I see two problems: 
> 
> 1) If someone uses gpu-switch (https://github.com/0xbb/gpu-switch) with this
> bug screen seem not work, after severals reboots (with different kernels) I can
> access a terminal and execute gpu-switch -d and then screen seems work again.
> 
> 2) If you use a Intel card (swiched with gpu-switch) the OSD (activated with
> functions keys) is so slow and chromium have the same problem (temporary fix is
> deactivate chromium hw acceleration) is this a intel driver bug?
> 
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Thanks,

-- 
Darren Hart
Intel Open Source Technology Center