[BUG 4.17] etnaviv-gpu f1840000.gpu: recover hung GPU!

[Russell King - ARM Linux]

On Tue, Jun 26, 2018 at 09:17:26AM +0100, Russell King - ARM Linux wrote:
> On Tue, Jun 19, 2018 at 02:28:46PM +0200, Lucas Stach wrote:
> > Agreed. I'll look into bringing back the process detection for 4.17
> > stable.
> > 
> > I'm still curious why the GC600 on the Dove is that slow. With
> > performance like this moving a big(ish) window on the screen must be a
> > horrible user experience.
> 
> This doesn't seem to be the cause - it seems that there's something
> going on with 4.17 that really is causing the Dove GC600 to get stuck.
> Reverting all the drivers/gpu/drm/etnaviv changes back to the 4.16
> state while keeping everything else the same results in no hangs,
> whereas increasing the timeout with 4.17 still results in hangs.
> 
> I'll try to find some time to bisect.

Sorry, it seems that my attempts to change what was running on the
system were ineffective (due to the etnaviv module loaded from the
initramfs, not from the fs copy I was updating.)  Extending the
timeout to 5 seconds does indeed stop the issue.

More importantly, it stops some memory corruption I've observed as
well, caused by etnaviv freeing buffers when it thinks the GPU has
timed out while the GPU is still writing to them.

-- 
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