Mythtv playing way to fast using DRM VBlank ioctl

[Michel Dänzer]

On Thu, 2006-03-30 at 18:26 -0500, Greg Stark wrote:
> Greg Stark <gsstark at MIT.EDU> writes:
> 
> > "Alex Deucher" <alexdeucher at gmail.com> writes:
> > 
> > > > So I just tried the March 30 snapshot and neither monitor gets a signal. Plus
> > > > as a bonus when I go back to merged frame Xv no longer works properly either.
> > 
> > Also, the Xv failure is interesting. It looks like somebody used the wrong
> > dimensions somewhere in calculating the overlay geometry. For instance, they
> > might have used the CRTC1 width instead of the overall framebuffer width.
> > 
> > The effect is to take the video and spray it across the framebuffer with part
> > of it where it belongs, then part of it further over, and so on iterating
> > across the screen. Actually It's probably actually looping across the screen
> > two or more times before landing back in sync with the original position.
> > 
> > The weird thing is that this doesn't just affect the XVideo overlay. There are
> > no artifacts until I use Xv but once I do then there are problems even after I
> > close the Xv window. Other applications with plain old X windows begin
> > exhibiting the same problem drawing their pixels across the framebuffer.
> > 
> > Also, it still happens even if I set NoAccel (which I will now turn off as
> > it's bugging the hell out of me:)

This sounds like https://bugs.freedesktop.org/show_bug.cgi?id=1992 ,
however...

> Hm, actually it doesn't seem to be tied to XVideo at all. Mplayer using XVideo
> doesn't trigger the problem. Only mythtv. That leads me to think it may be the
> VBlank ioctl that's corrupting some geometry info somewhere.
> 
> Moreover setting DMAForXv to off doesn't fix the problem. On the other hand
> removing the DRM and radeon modules before starting X does fix it.

... this doesn't but rather sounds related to colour tiling or
something. Does Option "ColorTiling" "off" work around this? If not, are
the symptoms permanent or intermittent? Can you get a screenshot of
this?


-- 
Earthling Michel Dänzer      |     Debian (powerpc), X and DRI developer
Libre software enthusiast    |   http://svcs.affero.net/rm.php?r=daenzer