Re: Radeon in LK 2.4.21pre7

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Sun, 2003-07-20 at 07:43, Kristofer T. Karas wrote:
> Ben, Ani, et al,
> 
> Just tried Linux kernels 2.4.21pre6 and pre7 with my Radeon 8500LEE and
> have had some dreadful corruption problems related to pixel clearing
> during scroll and ypan.  This is probably old news to you; so <aol>me
> too</aol>.  I first noticed this in the -ac kernels, but a variant is
> now in mainline -pre.
> 
> Problem #1:  When scrolling, radeonfb fails to erase the portion of the
> screen at the bottom, leaving all sorts of random pixels in the bottom
> line.  Further scrolling propagates these pixels upwards.
> See http://enterprise.bidmc.harvard.edu/~ktk/temp/radeonfb/screen-1.jpg
> (Sorry for camera-shake; hand-held in dim room...)

This looks like erase not working properly... This usually happens
after switching back from X as X tends to leave some garbage in some
engine registers, and is usually cured by switching to another console
(this is why I tend to force-reinit the accel engine on console switch).

Since your problem seem to not depend on XFree, I suspect something
else hairy is going on with the engine, I don't know what yet though,
I'll try to find some clue.

In the meantime, can you send me a dmesg output ?

Thanks,
Ben.