Radeon jittery post 2.6.35

Anders Eriksson aeriksson at fastmail.fm
Tue Mar 15 01:18:30 PDT 2011

 On 03/14/11 23:20, Alex Deucher wrote:
> On Sun, Mar 13, 2011 at 10:08 AM, Anders Eriksson <aeriksson at fastmail.fm> wrote:
>>  Hi,
>> I've found what I guess is a radeon (or drm/kms) regression post 2.6.35.
>> I've got my TV conneced to my RS690G over HDMI, and the display has
>> always been jittery after POST and at the GRUB screen. Pre-KMS, the X
>> server (or driver got it sorted), and when KMS started, the display
>> stabilized right after the kernel driver was initiated. However, post
>> 2.6.35, I see the jitter is back.
>> I've spent the last month trying to bisect it, but pretty much failed.
>> It appears that versions closer to 2.6.38-rcX are more prone to display
>> jitter, while 2.6.36 or so can have many successful runs. It also
>> appears to be related to device power-on order, or so I've come to
>> believe; A stable display can turn jittery, just by power cycling the TV.
>> I've uploaded a video of a 38-rc8 boot:
>> http://www.easy-share.com/1914220540/2.6.38-rc8_bad_x.mp4
>> You'll see jitter at the POST screen and GRUB. When KMS kicks in it
>> stabilizes, and when Freevo starts X, it's back to jitter.
> Does plain X or gnome/kde jitter too or just freevo?
Yes. A plain xinit with an xterm without window manager shows the same
thing. (I run freevo on on X, not fb)

Btw, These are the X packages I use:

> Alex
>> The jitter is always of the same kind. It looks like an old tv set which
>> loses sync. The contents on the display is, for a split second, placed
>> at the wrong part of the screen (vertically and to some extent
>> horizontally), and every 5-15 seconds or so, there is a big reset when
>> the TV tries to restart things (I guess). At the resets, thee is a loud
>> 'ping' in the nearby stereo too...
>> During the bisect  (and a t 38-rc8) I've seen this both at the console
>> (post KMS) and in X, so I'm not sure where the error is. I hope some of
>> you can get a better idea of where to hunt for the bug by looking at the
>> video.
>> -Anders

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