diff options
Diffstat (limited to 'src/mesa/drivers/dri/i965')
| -rw-r--r-- | src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c index 467ada5079b..a775d5589d5 100644 --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c @@ -2460,7 +2460,19 @@ intel_miptree_map_raw(struct brw_context *brw, struct intel_mipmap_tree *mt) if (drm_intel_bo_references(brw->batch.bo, bo)) intel_batchbuffer_flush(brw); - if (mt->tiling != I915_TILING_NONE) + /* brw_bo_map() uses a WB mmaping of the buffer's backing storage. It + * will utilize the CPU cache even if the buffer is incoherent with the + * GPU (i.e. any writes will be stored in the cache and not flushed to + * memory and so will be invisible to the GPU or display engine). This + * is the majority of buffers on a !llc machine, but even on a llc + * almost all scanouts are incoherent with the CPU. A WB write into the + * backing storage of the current scanout will not be immediately + * visible on the screen. The transfer from cache to screen is slow and + * indeterministic causing visible glitching on the screen. Never use + * this WB mapping for writes to an active scanout (reads are fine, so + * long as cache consistency is maintained). + */ + if (mt->tiling != I915_TILING_NONE || mt->is_scanout) brw_bo_map_gtt(brw, bo, "miptree"); else brw_bo_map(brw, bo, true, "miptree"); |