[Intel-gfx] [PATCH] drm/i915: paper over missed irq issues with force wake vodoo

[Keith Packard]

On Wed,  4 Jan 2012 17:52:10 +0100, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:

> Two things seem to do the trick on my ivb machine here:
> - prevent the gt from powering down while waiting for seqno
>   notification interrupts by grabbing the force_wake in get_irq (and
>   dropping it in put_irq again).
> - ordering writes from the ring's CS by reading a CS register, ACTHD
>   seems to work.
> 
> Only the blt&bsd ring on ivb seem to be massively affected by this,
> but for paranoia do this dance also on the render ring and on snb
> (i.e. all gpus with forcewake).
> 
> Tested with Eric's glCopyPixels loop which without this patch scores a
> missed irq every few seconds.
> 
> This patch needs my forcewake rework to use a spinlock instead of
> dev->struct_mutex.

I've pushed these to the forcewake-spinlock branch in both my fdo and
kernel repositories. Please give that a try on IVB and SNB to make sure
things are working right.

I'd like to get these into master as well as being sent off to stable@
for 3.2.x

-- 
keith.packard at intel.com
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