2009-01-05 08:39:26

by Tino Keitel

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Subject: 2.6.28 regression: xbacklight broken on ThinkPad X61s

Hi,

xbacklight is broken as of 2.6.28 on my ThinkPad X61s. It works with
2.6.27(.8) The difference I can see between both kernels is that 2.6.27
has 2 backlight ACPI devices, whereas 2.6.28 only has one device. With
2.6.28, I can use xbacklight and see the values change in xbacklight
-get, but the actual display brightness doesn't change.

Attached are 2 files with diagnostic output from 2.6.27 and 2.6.28. Any
hints how to solve or debug this?

Regards,
Tino


Attachments:
(No filename) (466.00 B)
backlight_2.6.27 (2.37 kB)
backlight_2.6.28 (1.64 kB)
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2009-01-05 09:05:17

by Zhang, Rui

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Subject: Re: 2.6.28 regression: xbacklight broken on ThinkPad X61s

On Mon, 2009-01-05 at 16:39 +0800, Tino Keitel wrote:
> Hi,
>
> xbacklight is broken as of 2.6.28 on my ThinkPad X61s. It works with
> 2.6.27(.8) The difference I can see between both kernels is that 2.6.27
> has 2 backlight ACPI devices, whereas 2.6.28 only has one device. With
> 2.6.28, I can use xbacklight and see the values change in xbacklight
> -get, but the actual display brightness doesn't change.
>
hmm, this regression is caused by commit
22c13f9d8179f4c9caecfcb60a95214562b9addc

but the real problem is that the IGD OpRegion doesn't work well on this
laptop.

please file a bug at bugzilla.kernel.org and attach the acpidump there.

thanks,
rui

2009-01-05 11:06:21

by Matthew Garrett

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Subject: Re: 2.6.28 regression: xbacklight broken on ThinkPad X61s

On Mon, Jan 05, 2009 at 05:06:15PM +0800, Zhang Rui wrote:

> hmm, this regression is caused by commit
> 22c13f9d8179f4c9caecfcb60a95214562b9addc
>
> but the real problem is that the IGD OpRegion doesn't work well on this
> laptop.

I suspect that the issue is actually that the opregion code works fine
but i915 interrupts are failing to work properly, which we've seen a
couple of cases of. Jesse?

--
Matthew Garrett | [email protected]