[Intel-gfx] [PATCH] Disable DRI2 buffer tiling on non-965, as those need fence regs for 2D blits.

[Eric Anholt]

On Tue, 2009-01-06 at 11:02 -0800, Jesse Barnes wrote:
> On Monday, January 5, 2009 11:30 pm Eric Anholt wrote:
> > This fixes glReadPixels failure on single-channel 915GM, as the software
> > code for readpixels was actually the only code in the driver doing tiling
> > against these buffers (everything else says "rely on fence registers",
> > since the 2D blits don't have a "don't rely on fence registers" option).
> > ---
> >  src/i830_dri.c |    9 +++++++++
> >  1 files changed, 9 insertions(+), 0 deletions(-)
> >
> > diff --git a/src/i830_dri.c b/src/i830_dri.c
> > index 0fe0eca..c4440ce 100644
> > --- a/src/i830_dri.c
> > +++ b/src/i830_dri.c
> > @@ -1883,6 +1883,15 @@ I830DRI2CreateBuffers(DrawablePtr pDraw, unsigned
> > int *attachments, int count) break;
> >  	    }
> >
> > +	    /* Disable tiling on 915-class 3D for now.  Because the 2D blitter
> > +	     * requires fence regs to operate, and they're not being managed
> > +	     * by the kernel yet, we don't want to expose tiled buffers to the
> > +	     * 3D client as it'll just render incorrectly if it pays attention
> > +	     * to our tiling bits at all.
> > +	     */
> > +	    if (!IS_I965G(pI830))
> > +		tiling = I915_TILING_NONE;
> > +
> >  	    if (tiling != I915_TILING_NONE) {
> >  		bo = i830_get_pixmap_bo(pPixmap);
> >  		drm_intel_bo_set_tiling(bo, &tiling,
> 
> Yeah, unfortunately we have to do this.  Have you thought anymore about how we 
> could deal with tiling on pre-965?  Maybe we could have separate memory areas 
> for X tiled and Y tiled objects and leave fences set up for them?

The problem is that fences are rectangular, and aperture space is
precious.  I think the only real solution is runtime fence management at
execbuf time, based on what you brought in with GTT mapping.  Seems like
it shouldn't be far from here to getting that working.

-- 
Eric Anholt
eric at anholt.net                         eric.anholt at intel.com


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
URL: <http://lists.freedesktop.org/archives/intel-gfx/attachments/20090106/968c00be/attachment.sig>