[Intel-gfx] [PATCH 05/12] drm/i915: Clear VLV_IER around irq processing

[Ville Syrjälä]

On Thu, Apr 14, 2016 at 10:36:00AM +0100, Chris Wilson wrote:
> On Wed, Apr 13, 2016 at 09:19:51PM +0300, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > On VLV/CHV the master interrupt enable bit only affects GT/PM
> > interrupts. Display interrupts are not affected by the master
> > irq control.
> > 
> > Also it seems that the CPU interrupt will only be generated when
> > the combined result of all GT/PM/display interrupts has a 0->1
> > edge. We already use the master interrupt enable bit to make sure
> > GT/PM interrupt can generate such an edge if we don't end up clearing
> > all IIR bits. We must do the same for display interrupts, and for
> > that we can simply clear out VLV_IER, and restore after we've acked
> > all the interrupts we are about to process.
> > 
> > So with both master interrupt enable and VLV_IER cleared out, we will
> > guarantee that there will be a 0->1 edge if any IIR bits are still set
> > at the end, and thus another CPU interrupt will be generated.
> > 
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Fixes: 579de73b048a ("drm/i915: Exit cherryview_irq_handler() after one pass")
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Ville is very persuasive,
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> Other than wishing the extra POSTING_READ and reading known registers
> away, the rest of the series is also
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Entire series pushed to dinq. Thanks for the review.

Let's keep our fingers crossed that this cures all the
current chv ailments.

-- 
Ville Syrjälä
Intel OTC