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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2014-08-07 15:39:54 +0100 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-09-04 11:26:17 +0200 |
| commit | 95468892fdfeef6d1004b524e35957629efdbe00 (patch) | |
| tree | e4c252187e534b940c9553bd0df70df5d57cd315 | |
| parent | 4ad72b7fadd285f849439cdbc408f8b847cef704 (diff) | |
| download | linux-rt-95468892fdfeef6d1004b524e35957629efdbe00.tar.gz | |
drm/i915: Reset the HEAD pointer for the ring after writing START
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@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
| -rw-r--r-- | drivers/gpu/drm/i915/intel_ringbuffer.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index f8aadc3c2124..85fc2b1a124a 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -563,6 +563,14 @@ 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); |