[PATCH 1/3] drm/i915: Handle GEN6_PMINTRMSK for proper masking of RPS interrupts with GuC submission

[Chris Wilson]

On Mon, Jan 16, 2017 at 04:08:39PM +0530, Kamble, Sagar A wrote:
> 
> 
> On 1/16/2017 3:43 PM, Chris Wilson wrote:
> >WARN_ON(dev_priv->gt.awake);
> Could you please clarify why this check is needed.
> During reset, when GuC is getting loaded, GT.awake can be true.
> >WARN_ON(I915_READ(GEN6_PMINTRMSK) != ~dev_priv->rps.pm_intr_keep);
> GEN6_PMINTRMSK will have varying bitmasks based on freq request so
> very likely this WARN will be hit.

Hmm, this was paranoia to try and assert that we knew when we where
fiddling with registers, and in particular that no one else was also
fiddling with them - we don't hold the rps.mutex for example.

I think we need to hold rps.mutex then.

> >I915_WRITE(GEN6_PMINTRMSK, ~GEN8_PMINTR_REDIRECT_TO_GUC); /* clear for guc_interrupts capture() */
> >...
> >I915_WRITE(GEN6_PMINTRMSK, ~dev_priv->rps.pm_intr_keep);
> Agree with above two writes logic.

Apart from that we can be here with gt.awake, and so we need the save
and (restore & mask). More craziness now with reset triggering new hw
state and trying to replay the existing requests. :|
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre