[Xorg-driver-geode] Glitch over text areas

[Mart Raudsepp]

On N, 1970-01-01 at 00:00 +0000, Mart Raudsepp wrote:
> On N, 1970-01-01 at 00:00 +0000, Tomas E. Caram wrote:
> > 
> > After a lot of trial and error i got my geode video card working, but
> > now i have some kind of glitch over icons and text areas. 
> > 
> > My hardware:  PackardBell s18p, also known as: VYE S18 , Kohjinsha
> > SA1F00 and other re-branded names of "s18p" 
> > 
> > 
> > 
> > Example of the glitch: http://i.imgur.com/hD30V.jpg 
> 
> I can reproduce this easily as well in firefox and GtkLabels after
> having recently upgraded to cairo-1.12. I believe we are suffering from
> a similar problem in our driver than even some mainstream ones did[1],
> and I meant to make sure we don't after I upgraded to cairo-1.12. Now
> that I have, I'll take a closer look on solving this soon.
> 
> 
> [1] https://bugs.freedesktop.org/show_bug.cgi?id=47266

It is indeed quite surely that bug.

In summary, cairo-1.12 started using solid pictures instead of 1x1
repeated pictures in many cases, including code paths that end up doing
glyph rendering.

The generic EXA fallback code has still a bug in handling the fallback
of those solid pictures in this situation, and in Geode we still
fallback it as we do not have hardware acceleration code for this
situation (as no-one has yet thought about its implementation, as before
cairo-1.12 apparently practically nothing made use of this).

So technically the glitch on text areas is the cause of xserver, however
in practice we should really try to implement solid pictures now.
While xserver should still be fixed to not cause rendering issues if a
driver fallbacks on solid picture, we really should get solid pictures
acceleration implemented now. It is very important to the performance of
text and some other rendering now with cairo-1.12.
It should be possible with a 1x1 repeat pattern image in scratch area or
so, but there may be even better methods for our hardware - needs
research.



Best,
Mart Raudsepp