[Intel-gfx] KMS broken from 2.6.33 up to 2.6.35-rc5????

[Massimo Maggi]

 After 14 builds (never tought that PXE and Core2Quad were so
useful!!).... the bad commit is:

01c66889c14aa163c49355b3be2ccfb214500599 is the first bad commit
commit 01c66889c14aa163c49355b3be2ccfb214500599
Author: Zhao Yakui <yakui.zhao at intel.com>
Date:   Wed Oct 28 05:10:00 2009 +0000

    drm/i915: Add ACPI OpRegion support for Ironlake
   
    Add the support of ACPI opregion on Ironlake so that the backlight
    brightness can be adjusted by using ACPI interface
       >/sys/class/backlight/acpi_video0/brightness
   
    Signed-off-by: Zhao Yakui <yakui.zhao at intel.com>
    Tested-by: Zhao Yakui <yakui.zhao at intel.com>
    [zhenyuw: cleanups, fix typo for checking GSE irq and convert to
    current irq handling logic.]
    Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
    Signed-off-by: Eric Anholt <eric at anholt.net>

:040000 040000 79f96cd37f779fb2b33f0e6545e83f32cd5c1372
3b9f77adfeed13386058a46a17e3f4facd8d862c M      drivers

The problem is *half*-solved...
connecting by ssh (as root) and typing
# echo -n 10 >/sys/class/backlight/acpi_video0/brightness
revives the screen.
Starting X gives me a fully working KWin compositing (with OpenGL)
I will temporarily put this line in an init script, but I think that
this bug must be solved as soon as possible!
Another question:
How can I be sure that the ATI gpu isn't wasting power while PC is
booted in Linux?
Best regards,
Massimo Maggi
massimo at mmmm.it


Il 18/07/2010 14:57, Chris Wilson ha scritto:
> On Sun, 18 Jul 2010 14:29:34 +0200, Massimo Maggi <massimo at mmmm.it> wrote:
>> I've set up a very minimal kernel config (the resulting kernel is not
>> useful for anything except showing the problem), and built versions:
>> 2.6.32.16
>> 2.6.33.6
>> 2.6.34.1
>> 2.6.35-rc5
>> Only 2.6.32.16 is able to correctly initialize the framebuffer.
> Excellent, as you have managed to reproduce this with a minimal kernel,
> can you do a bisect between 2.6.33.16 and 2.6.33.6 and see which patch
> causes the regression? It should only take a couple of hours. My bet is
> one of the Arrandale enabling patches...
>

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