Radeon jittery post 2.6.35

Alex Deucher alexdeucher at gmail.com
Mon Mar 14 15:20:33 PDT 2011

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?


> 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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