On Thu, Aug 07, 2014 at 03:39:54PM +0100, Chris Wilson wrote: > Ville found an old w/a documented for g4x that suggested that we need to > reset the HEAD after writing START. This is a useful fixup for some of > the g4x ring initialisation woes, but as usual, not all. > > v2: Do the rewrite unconditionally anyway > > References: https://bugs.freedesktop.org/show_bug.cgi?id=76554 > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Yeah looks sensible to me. So based on my gut feeling just from the seeing the w/a name this is: Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_ringbuffer.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c > index 45e3ec927051..26ec25afc02a 100644 > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c > @@ -537,6 +537,14 @@ static int init_ring_common(struct intel_engine_cs *ring) > * also enforces ordering), otherwise the hw might lose the new ring > * register values. */ > I915_WRITE_START(ring, i915_gem_obj_ggtt_offset(obj)); > + > + /* WaClearRingBufHeadRegAtInit:ctg,elk */ > + if (I915_READ_HEAD(ring)) > + DRM_DEBUG("%s initialization failed [head=%08x], fudging\n", > + ring->name, I915_READ_HEAD(ring)); > + I915_WRITE_HEAD(ring, 0); > + (void)I915_READ_HEAD(ring); > + > I915_WRITE_CTL(ring, > ((ringbuf->size - PAGE_SIZE) & RING_NR_PAGES) > | RING_VALID); > -- > 2.1.0.rc1 -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
