[Patch] i915gm: framebuffer compression+tiling on exa

[Jesse Barnes]

On Thursday, November 01, 2007 5:33 pm Peter Clifton wrote:
> On Thu, 2007-11-01 at 12:11 -0700, Jesse Barnes wrote:
> > On Thursday, November 01, 2007 11:45 Pierre Willenbrock wrote:
> > > Hi list,
> > >
> > > i am using latest git of xserver, xf86-video-intel, drm and mesa.
> > > Since the merge of bufferobjects and support code into drm and
> > > xf86-video-intel, i was unable to use tiling. After looking at bug
> > > #12994 i found that i tried to disable framebuffer compression by
> > > disabling the option "Compression" instead of
> > > "FramebufferCompression", so i tried again, and found that i could
> > > use either framebuffer compression or tiling, but not both.
> > >
> > > Digging deeper into the driver sources, i found #define
> > > FBC_CTL_FENCENO, which was not used anywhere. So i tried adding the
> > > fence number of my frambuffer(3) to the FBC control register, which
> > > made the FBC and tiling work at the same time. A patch is attached.
> >
> > Ah, excellent!  That definitely explains the bad behavior several people
> > have been seeing.  Earlier (I think I even had a comment to this effect
> > at one point) I assumed that the front buffer was using fence 0.  This
> > looks like a real fix.  I'll go ahead and check it in.
>
> Sorry to be annoying, but do you mind quickly explaining what "bad
> behaviour" this results in? (IE. is it a fix we need to backport for
> Ubuntu to fix bugs users might hit?)

Bad behavior would be display corruption or something that looked like a hang.  
Backporting wouldn't hurt, but I don't think earlier driver versions will be 
affected since they tend to put the framebuffer address in fence register 0.

Jesse