Re: Linux 2.6.35-rc2

From: Torsten Kaiser
Date: Mon Jun 07 2010 - 02:09:53 EST


On Mon, Jun 7, 2010 at 7:58 AM, Alex Deucher <alexdeucher@xxxxxxxxx> wrote:
> On Sun, Jun 6, 2010 at 11:04 AM, Torsten Kaiser
> <just.for.lkml@xxxxxxxxxxxxxx> wrote:
>> [CC:Jeff+Tejun not removed, because you might want to look at the
>> attached dmesgs]
>>
>> On Sun, Jun 6, 2010 at 4:19 PM, Linus Torvalds
>> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>> On Sun, 6 Jun 2010, Torsten Kaiser wrote:
>>>>
>>>> The first problem that shows up is, that after the KMS switches to the
>>>> correct video mode (1280x1024 for an DVI attached LCD), the display
>>>> begins to flicker. Every 1..2 seconds (guesstimated) the display turns
>>>> off and on again. Something in the new powersaving?
>>>
>>> Or maybe a borderline display timing that the display has trouble syncing
>>> up with?
>>
>> With 2.6.34 and any previous KMS kernels the output was always stable.
>> (I think, I switch to the radeon KMS on 2.6.32)
>> The onscreen menu of the monitor showed 1280x1024@xxxxxx for
>> 2.6.35-rc2, if I recall correctly.
>> Now back on 2.6.34 its 1280x1024@xxxxxxx
>
> The pm code shouldn't have any affect as your system only has one
> power state, so it never kicks in.  It sounds like a display pll
> problem, but there haven't been any changes to that code since 2.6.34.
>  Any chance you could bisect it?

Not really. -rc1 did not boot for me (although if I disable v4l that
might work), and there is this memory corruption error.

Regarding the PLLs, did you see this mail? It contains the
drm.debug=15 output from 2.6.34 and 2.6.35-rc2.
http://lkml.org/lkml/2010/6/6/126

The debug output from radeon_set_pll looks identical. But in 2.6.35 a
call to [drm:radeon_legacy_tmds_int_dpms], seems new.

The switchoff intervall is ~10 seconds, not 1..2 as I guessed in the first mail.
Any idea if there is something in the KMS code that triggers at this intervall?

Torsten
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