[PATCH] drm/i915: Don't forget to apply SNB PIPE_CONTROL GTT workaround.

Eric Anholt
2012-07-31T01:24:26Z

If a buffer that was the target of a PIPE_CONTROL from userland was a
reused one that hadn't been evicted which had not previously had this
workaround applied, then we would not bind it into the GTT and the
write would land somewhere else.

Based on a doubting-my-sanity debugging session with cworth, I'm
pretty sure this will fix his reproducible GL_EXT_timer_query
failures, and hopefully the intermittent OQ issues on snb that
danvet's been working on.

I have not tested it yet, but hopefully when cworth gets home he will.

Signed-off-by: Eric Anholt <eric@anholt.net>
---
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 25b2c54..afb312e 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -117,6 +117,16 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
target_i915_obj = to_intel_bo(target_obj);
target_offset = target_i915_obj->gtt_offset;

+ /* Sandybridge PPGTT errata: We need a global gtt mapping for MI and
+ * pipe_control writes because the gpu doesn't properly redirect them
+ * through the ppgtt for non_secure batchbuffers. */
+ if (unlikely(IS_GEN6(dev) &&
+ reloc->write_domain == I915_GEM_DOMAIN_INSTRUCTION &&
+ !target_i915_obj->has_global_gtt_mapping)) {
+ i915_gem_gtt_bind_object(target_i915_obj,
+ target_i915_obj->cache_level);
+ }
+
/* The target buffer should have appeared before us in the
* exec_object list, so it should have a GTT space bound by now.
*/
@@ -225,16 +235,6 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
io_mapping_unmap_atomic(reloc_page);
}

- /* Sandybridge PPGTT errata: We need a global gtt mapping for MI and
- * pipe_control writes because the gpu doesn't properly redirect them
- * through the ppgtt for non_secure batchbuffers. */
- if (unlikely(IS_GEN6(dev) &&
- reloc->write_domain == I915_GEM_DOMAIN_INSTRUCTION &&
- !target_i915_obj->has_global_gtt_mapping)) {
- i915_gem_gtt_bind_object(target_i915_obj,
- target_i915_obj->cache_level);
- }
-
/* and update the user's relocation entry */
reloc->presumed_offset = target_offset;

--
1.7.10.4