Re: [PATCH] Dont use hardware acceleration on Sandybridge rev 07 hardware or earlier.

[Matthias Hopf <mhopf@suse.de>]

On Nov 19, 10 21:47:48 +0000, Chris Wilson wrote:
> On Fri, 19 Nov 2010 04:29:57 +0100, Matthias Hopf <mhopf@suse.de> wrote:
> > This is known to lock up the GPU even with the workaround in place.
> 
> Before applying this patch, I'd like to know the results of using the
> FORCE_WAKE write before reading the ring buffer registers. Also as we are
> accumulating workarounds for SNB faster than is healthy, we should be
> careful about which one we mean at the time of the comment.

I know, I know. The patch is (one of) the results of the Novell-HP-Intel
workshop in Taipei this week. It turned out that rev07 is too unstable.
Keith and Eric can probably comment on this. Better than I can.

I'm currently unsure whether the FORCE_WAKE write is the workaround
Eric was testing, but we used his intel_drm_next branch for that.
Without that workaround in place the rev07 locked up basically
immediately, while with the workaround it took a while (though not very
long) to freeze the GPU.

Strictly speaking the patch is possibly not really required for
upstream, as it's only about rev07. We will use it to be able to
continue testing at Novell with these old revisions.

Thanks

CU

Matthias

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