Re: [PATCH 12/15] drm/i915: Interrupt routing for GuC submission

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jun 17, 2015 at 09:20:44AM +0100, Dave Gordon wrote:
> On 16/06/15 10:24, Chris Wilson wrote:
> > On Mon, Jun 15, 2015 at 07:36:30PM +0100, Dave Gordon wrote:
> >> +static void direct_interrupts_to_guc(struct drm_i915_private *dev_priv)
> >> +{
> >> +	struct intel_engine_cs *ring;
> >> +	int i, irqs;
> >> +
> >> +	/* tell all command streamers to forward interrupts and vblank to GuC */
> >> +	irqs = _MASKED_FIELD(GFX_FORWARD_VBLANK_MASK, GFX_FORWARD_VBLANK_ALWAYS);
> >> +	irqs |= _MASKED_BIT_ENABLE(GFX_INTERRUPT_STEERING);
> >> +	for_each_ring(ring, dev_priv, i)
> >> +		I915_WRITE(RING_MODE_GEN7(ring), irqs);
> >> +
> >> +	/* tell DE to send (all) flip_done to GuC */
> >> +	irqs = DERRMR_PIPEA_PRI_FLIP_DONE | DERRMR_PIPEA_SPR_FLIP_DONE |
> >> +	       DERRMR_PIPEB_PRI_FLIP_DONE | DERRMR_PIPEB_SPR_FLIP_DONE |
> >> +	       DERRMR_PIPEC_PRI_FLIP_DONE | DERRMR_PIPEC_SPR_FLIP_DONE;
> >> +	/* Unmasked bits will cause GuC response message to be sent */
> >> +	I915_WRITE(DE_GUCRMR, ~irqs);
> > 
> > That's scary since userspace depends on a few more DERRMR events
> > (wait-for-scanline). Where will they end up?
> > -Chris
> 
> This doesn't change any bits in DE_RRMR, or set the VBLANK or SCANLINE
> bits in the DE_GUCRMR, so those events should be unaffected. The GuC
> isn't interested in those, only in flip done.

Why does the guc care about flip_done? With atomic it'll get exactly none
of those, ever ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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