[Intel-gfx] [PATCH v2] drm/i915: Clear lost context-switch interrupts across reset

[Chris Wilson]

Quoting Michel Thierry (2017-08-18 17:31:38)
> On 18/08/17 02:05, Chris Wilson wrote:
> > During a global reset, we disable the irq. As we disable the irq, the
> > hardware may be raising a GT interrupt that we then ignore, leaving it
> > pending in the GTIIR. After the reset, we then re-enable the irq,
> > triggering the pending interrupt. However, that interrupt was for the
> > stale state from before the reset, and the contents of the CSB buffer
> > are now invalid.
> > 
> > v2: Add a comment to make it clear that the double clear is purely my
> > paranoia.
> 
> Or say I was the paranoid.
> 
> > 
> > Reported-by: "Dong, Chuanxiao" <chuanxiao.dong at intel.com>
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: "Dong, Chuanxiao" <chuanxiao.dong at intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Michal Winiarski <michal.winiarski at intel.com>
> > Cc: Michel Thierry <michel.thierry at intel.com>
> > Link: https://patchwork.freedesktop.org/patch/msgid/20170807121919.30165-1-chris@chris-wilson.co.uk
[snip]
> Reviewed-by: Michel Thierry <michel.thierry at intel.com>

Marked it up with
Fixes: 821ed7df6e2a ("drm/i915: Update reset path to fix incomplete requests")
as though the likelihood is very low, we might as well be accurate.

Thanks for the review, and many thanks to Chuanxiao for spotting the
issue. Pushed.
-Chris