Re: [Dri-devel] Radeon state change lockup: new theory

[Dieter <Die...@ha...>]

Am Samstag, 03. Januar 2004 04:52 schrieb Felix K=FChling:
> Hi,
>
> this is referring to the a very reproducable lockup that occurred with
> glaxium on r100 hardware. Several months ago I tracked it down to
> emission of state changes and introduced a workaround that waits for 3D
> idle before state changes. Now I had a new idea about a possible cause
> of trouble: the order in which state atoms are emitted. And it appears I
> was right. :) I made a small hack that forces state attoms to be emitted
> in a fixed order and dropped the wait for 3D idle. The lockups are still
> gone and frame rates have increased significantly.
>
> A patch is attached. The order in which state atoms are emitted now is
> pretty arbitrary. It may be worth finding out exactly which permutations
> of state changes trigger the lockup. In the interest of security we
> could detect them in the DRM driver and emit a 3D idle to prevent an
> engine lockup. Finding all these permutations would take a lot of time
> (and reboots) though and it may even be too late to prevent a lockup
> when such a condition is detected. But maybe someone with hardware docs
> has a good guess, like dependencies of different state change commands
> that could cause inconsistencies if certain pairs of them are emitted in
> the wrong order.
>
> On the other hand we may just clean up my hack and be content with it.
> How do people feel about this?

Do you think that this could be useful for r200, too?

Greetings,
	Dieter