[PATCH] Ensure blitter quiescience before reading pixels from the framebuffer

[Bernardo Innocenti]

Dan Amelang wrote:

> At the X dev conference next month, I'll be presenting jitblt, which
> might solve your slow 16bpp problem. It's basically a pixman "backend"
> that JIT compiles specialized fast paths for any given format. Since
> both cairo and X use pixman for software compositing, jitblt-pixman
> should get you a boost across the board.

This is very good news!  Is the code available somewhere?

Carl may want to correct me on this, but I thought Cairo does not fully
support 16bpp rendering and will keep submitting 32bpp pixmaps to X even
when the screen is 16bpp.

I guess 16bpp in r5g6b5 is probably unsuitable for Cairo because
of the missing alpha channel.  The Geode GPU also supports an
r4g4b4a4 mode, but it's not supported in the driver and, as far as
I know, totally unsupported all over the rest of Xorg's code base.


> I'll be visiting the OLPC offices later this month, so I can bring a
> jitblt-enabled OLPC with me if you or Jim or whoever might be
> interested.

Looking forward to meet you!  I'm currently in Italy, but I'll be back
at the OLPC offices on August the 8th.

-- 
   // Bernardo Innocenti
 \X/  http://www.codewiz.org/