Glitch in newer drm-next/drm-radeon-testing

[Michel Dänzer]

On Mit, 2010-06-02 at 08:07 +0200, Marius Gröger wrote: 
> Hello All,
> 
> I'm trying the top-of-trunk drm-2.6 trees (both drm-next and
> drm-radeon-testing) with my Radeon HD 3200 GPU over HDMI. The primary
> application is mythtv which uses DRM syncing for the frame
> syncronisation. Now, with the exact same userland software I noticed the
> introduction of sync gliches in the May-timeframe. The
> drm-radeon-testing on May 9 was still ok, but both drm-next and
> drm-radeon-testing at the end of May showed that glitch: every couple of
> seconds there's a very visual hickup, especially in scroll texts.
> 
> Apologies for such an unspecific description, and for what almost seems
> like a support request for MythTV. I wouldn't post here if I were not
> 100% sure it must be related with the recent drm changes.

Note that the DRM APIs are intended for use by userspace components of
graphics drivers / API libraries, not applications directly. MythTV
shouldn't use the DRM directly for synchronization but rather use GLX
synchronization APIs.


> What I've tried so far:
> 
> * I tried bisecting, but I failed to spot the offending commits somehow.
> My last hope is this list of experts - for me the git logs look sane,
> but you guy surely have more insight.
> 
> * I tried turning on drm debug=1, but did not see anything suspicious,
> especially with relation to the r600 irq handling changes.
> 
> * Currently I'm in the process of setting up systemtap to profile the
> scheduling, but I'm still on the learning curve  :)
> 
> I'd be most grateful for any tips and things to try to isolate this issue.

If you have dynamic PM enabled, does disabling that help?


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer