[Intel-gfx] 16bpp and 8bpp uxa output broken...

[Daniel Vetter]

On Mon, Nov 4, 2013 at 12:56 AM, Thomas Richter <thor at math.tu-berlin.de> wrote:
>
> just another note: I just switched the default depth from 24 to 16 bit by
> adding a "DefaultDepth" into
> the screen section of X11. Strangely enough, that gives much *less* banding
> than the 24bpp output????

That just means we dither down in sw/hw to 16 bit, instead of
rendering at 24 and then doing no dithering at all.

> Anyhow, 16bpp breaks the gdm login, and 8bpp breaks almost everything.
> Strangely, if I switch from uxa
> to sna, gdm is fine and the graphics is much smoother (less banding) than
> with 24bpp output.

Iirc SNA enables all the neat hw dithering options. It also works
correctly at 16 bit, although you'll run into trouble with qt/kde
stuff and with opengl apps.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch