915gm/945gm/XAA lockup with gray blocks when switching video mode

[Jesse Barnes]

On Thursday, October 11, 2007 9:43 pm Bryce Harrington wrote:
> I tried adding a usleep(20) inside the loops, but the issue still
> came up (seemed like it took more attempts than normal to trigger,
> but that is hard to judge).
>
> I'll also try replacing the pallet restore loops.
>
> Could you also explain a bit more about what this pallet is?

Err, I meant palette. :)  It's just a guess, but it seems like banging 
on those registers causes problems for some people, but only some of 
the time.  This may be because you just happen to hit the issue during 
those PIOs or because the PIOs themselves are causing a problem 
somehow.  The latter might be due to the associated pipe being off, 
which would disable the registers, possibly causing a GPU crash when 
you wrote them (the fact that your crashes go away 100% points to this 
possibility).  The former would be some other problem probably caused 
by earlier code that we just happen to hit when doing the palette 
restoration...  putting delays before palette restore might confirm or 
deny that theory.

Jesse