[PATCH v4 2/6] drm/i915/gt: Ensure memory quiesced before invalidation

[Matt Roper]

On Mon, Jul 17, 2023 at 10:54:37AM -0700, Matt Roper wrote:
> On Mon, Jul 17, 2023 at 07:30:55PM +0200, Andi Shyti wrote:
> > From: Jonathan Cavitt <jonathan.cavitt at intel.com>
> > 
> > All memory traffic must be quiesced before requesting
> > an aux invalidation on platforms that use Aux CCS.
> > 
> > Fixes: 972282c4cf24 ("drm/i915/gen12: Add aux table invalidate for all engines")
> > Signed-off-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
> > Signed-off-by: Andi Shyti <andi.shyti at linux.intel.com>
> > Cc: <stable at vger.kernel.org> # v5.8+
> > ---
> >  drivers/gpu/drm/i915/gt/gen8_engine_cs.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> > index 563efee055602..bee3b7dc595cf 100644
> > --- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> > +++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> > @@ -202,6 +202,13 @@ int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
> >  {
> >  	struct intel_engine_cs *engine = rq->engine;
> >  
> > +	/*
> > +	 * Aux invalidations on Aux CCS platforms require
> > +	 * memory traffic is quiesced prior.
> > +	 */
> > +	if ((mode & EMIT_INVALIDATE) && !HAS_FLAT_CCS(engine->i915))
> 
> It's a pre-existing mistake in drm-tip at the moment, but we shouldn't
> assume !flatccs always implies auxccs.  PVC has neither, and there may
> be other similar platforms in the future.  We should probably add a
> helper function for AuxCCS, similar to what we added to the Xe driver
> recently:
> 
> https://patchwork.freedesktop.org/patch/539304/?series=118334&rev=1
> 

BTW, since this patch didn't handle it I was expecting to see another
patch in the series that quiesces memory for the non-RCS/CCS engines,
but it looks like there isn't one yet.  So we should probably add the
necessary MI_FLUSH_DW logic for the other engines to this patch as well.


Matt

> 
> Matt
> 
> 
> > +		mode |= EMIT_FLUSH;
> > +
> >  	if (mode & EMIT_FLUSH) {
> >  		u32 flags = 0;
> >  		int err;
> > -- 
> > 2.40.1
> > 
> 
> -- 
> Matt Roper
> Graphics Software Engineer
> Linux GPU Platform Enablement
> Intel Corporation

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation