Bug 63941

Summary: Can't control brightness with ATI 5650/Intel Ironlake when switched to radeon
Product: Drivers Reporter: Nikolay Amiantov (nikoamia)
Component: Video(DRI - non Intel)Assignee: drivers_video-dri
Status: RESOLVED OBSOLETE    
Severity: normal CC: alexdeucher, intel-gfx-bugs, nikoamia, szg00000
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 3.12-git Subsystem:
Regression: No Bisected commit-id:
Attachments: lspci
attachment-21199-0.html

Description Nikolay Amiantov 2013-10-28 13:38:16 UTC 
Created attachment 112531 [details]
lspci

I have hybrid ATI 5650/Intel Ironlake muxed system, and when I switch to radeon, backlight stays enabled now (looks like it have been fixed in https://bugzilla.kernel.org/show_bug.cgi?id=55311), but I can't change levels at all, and it becomes disabled when I do suspend cycle.
ls /sys/class/backlight:
acpi_video0 acpi_video1 intel_backlight
Neither of them work.
Comment 1 Nikolay Amiantov 2013-10-28 15:48:39 UTC 
Interesting enough, if unused Intel card is powered up, brightness works properly.
Comment 2 Nikolay Amiantov 2013-10-28 15:50:26 UTC 
Checked this on latest 3.12-git (aff22d3)
Comment 3 Jani Nikula 2013-10-29 06:40:34 UTC 
(In reply to Nikolay Amiantov from comment #1)
> Interesting enough, if unused Intel card is powered up, brightness works
> properly.

It looks like i915 is in control of the backlight. Either it was designed this way, or there's an additional mux that needs switching for backlight, or something else... I don't really know.

Reassigning to non-Intel, maybe the Radeon folks have more clues?
Comment 4 Alex Deucher 2013-10-29 13:32:18 UTC 
The radeon driver should add a backlight control if the platform utilizes the GPU's backlight controller.  If there is no radeon backlight interface, the platform uses some OEM specific backlight control (probably Intel or ACPI).  I suspect you will have to use the intel backlight control to control the backlight.
Comment 5 Nikolay Amiantov 2013-10-29 13:50:44 UTC 
Created attachment 112661 [details]
attachment-21199-0.html

Is there any way to trace ACPI calls and Intel card state (enabled or not)
on Windows? It works there, so maybe I can get some information.
29.10.2013 17:32 пользователь <bugzilla-daemon@bugzilla.kernel.org> написал:

> https://bugzilla.kernel.org/show_bug.cgi?id=63941
>
> Alex Deucher <alexdeucher@gmail.com> changed:
>
>            What    |Removed                     |Added
>
> ----------------------------------------------------------------------------
>                  CC|                            |alexdeucher@gmail.com
>
> --- Comment #4 from Alex Deucher <alexdeucher@gmail.com> ---
> The radeon driver should add a backlight control if the platform utilizes
> the
> GPU's backlight controller.  If there is no radeon backlight interface, the
> platform uses some OEM specific backlight control (probably Intel or
> ACPI).  I
> suspect you will have to use the intel backlight control to control the
> backlight.
>
> --
> You are receiving this mail because:
> You are on the CC list for the bug.
> You reported the bug.
>
Comment 6 Nikolay Amiantov 2013-10-29 13:52:03 UTC 
Comment on attachment 112661 [details]
attachment-21199-0.html

Replied from GMail and this happened, sorry.
Comment 7 Jani Nikula 2016-10-28 12:40:01 UTC 
Really old bug, closing.

Please file any remaining drm/i915 bugs at https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel