Re: [PATCH] drm/i915: FBC flush nuke for BDW

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Aug 01, 2014 at 05:07:30PM +0300, Ville Syrjälä wrote:
> On Thu, Jul 31, 2014 at 12:07:44PM -0700, Rodrigo Vivi wrote:
> > According to spec FBC on BDW and HSW are identical without any gaps.
> > So let's copy the nuke and let FBC really start compressing stuff.
> > 
> > Without this patch we can verify with false color that nothing is being
> > compressed. With the nuke in place and false color it is possible
> > to see false color debugs.
> > 
> > v2: Fix rebase conflict.
> > 
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_ringbuffer.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > index 2908896..4ba3db1 100644
> > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > @@ -406,6 +406,7 @@ gen8_render_ring_flush(struct intel_engine_cs *ring,
> >  {
> >  	u32 flags = 0;
> >  	u32 scratch_addr = ring->scratch.gtt_offset + 2 * CACHELINE_BYTES;
> > +	int ret;
> >  
> >  	flags |= PIPE_CONTROL_CS_STALL;
> >  
> > @@ -424,7 +425,14 @@ gen8_render_ring_flush(struct intel_engine_cs *ring,
> >  		flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;
> >  	}
> >  
> > -	return gen8_emit_pipe_control(ring, flags, scratch_addr);
> > +	ret = gen8_emit_pipe_control(ring, flags, scratch_addr);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (!invalidate_domains && flush_domains)
> > +		return gen7_ring_fbc_flush(ring, FBC_REND_NUKE);
> > +
> > +	return 0;
> >  }
> >  
> >  static void ring_write_tail(struct intel_engine_cs *ring,
> > @@ -2065,7 +2073,7 @@ static int gen6_ring_flush(struct intel_engine_cs *ring,
> >  	}
> >  	intel_ring_advance(ring);
> >  
> > -	if (IS_GEN7(dev) && !invalidate && flush)
> > +	if (INTEL_INFO(dev)->gen >= 7 && !invalidate && flush)
> >  		return gen7_ring_fbc_flush(ring, FBC_REND_CACHE_CLEAN);
> 
> Apparently BDW has problems with LRIs to certain register offsets on
> !RCS and this here would hit that. The suggested workaround is to emit
> such LRIs only from RCS. Doing that would also involve tossing in a
> semaphore, so it feels like something that ought to be handled
> somewhere a bit higher up.

*cough* sw frontbuffer tracking *cough*

At least with fbc we have this nice igt test already.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch