diff options
| -rw-r--r-- | src/mesa/drivers/dri/i965/intel_pixel_read.c | 24 | ||||
| -rw-r--r-- | src/mesa/drivers/dri/i965/intel_tex_image.c | 9 |
2 files changed, 31 insertions, 2 deletions
diff --git a/src/mesa/drivers/dri/i965/intel_pixel_read.c b/src/mesa/drivers/dri/i965/intel_pixel_read.c index d3ca38b6ecd..30380570d62 100644 --- a/src/mesa/drivers/dri/i965/intel_pixel_read.c +++ b/src/mesa/drivers/dri/i965/intel_pixel_read.c @@ -226,8 +226,30 @@ intelReadPixels(struct gl_context * ctx, if (_mesa_is_bufferobj(pack->BufferObj)) { if (_mesa_meta_pbo_GetTexSubImage(ctx, 2, NULL, x, y, 0, width, height, 1, - format, type, pixels, pack)) + format, type, pixels, pack)) { + /* _mesa_meta_pbo_GetTexSubImage() implements PBO transfers by + * binding the user-provided BO as a fake framebuffer and rendering + * to it. This breaks the invariant of the GL that nothing is able + * to render to a BO, causing nondeterministic corruption issues + * because the render cache is not coherent with a number of other + * caches that the BO could potentially be bound to afterwards. + * + * This could be solved in the same way that we guarantee texture + * coherency after a texture is attached to a framebuffer and + * rendered to, but that would involve checking *all* BOs bound to + * the pipeline for the case we need to emit a cache flush due to + * previous rendering to any of them -- Including vertex, index, + * uniform, atomic counter, shader image, transform feedback, + * indirect draw buffers, etc. + * + * That would increase the per-draw call overhead even though it's + * very unlikely that any of the BOs bound to the pipeline has been + * rendered to via a PBO at any point, so it seems better to just + * flush here unconditionally. + */ + intel_batchbuffer_emit_mi_flush(brw); return; + } perf_debug("%s: fallback to CPU mapping in PBO case\n", __func__); } diff --git a/src/mesa/drivers/dri/i965/intel_tex_image.c b/src/mesa/drivers/dri/i965/intel_tex_image.c index 7952ee5ad88..85d3d04ecb3 100644 --- a/src/mesa/drivers/dri/i965/intel_tex_image.c +++ b/src/mesa/drivers/dri/i965/intel_tex_image.c @@ -486,8 +486,15 @@ intel_get_tex_image(struct gl_context *ctx, if (_mesa_meta_pbo_GetTexSubImage(ctx, 3, texImage, 0, 0, 0, texImage->Width, texImage->Height, texImage->Depth, format, type, - pixels, &ctx->Pack)) + pixels, &ctx->Pack)) { + /* Flush to guarantee coherency between the render cache and other + * caches the PBO could potentially be bound to after this point. + * See the related comment in intelReadPixels() for a more detailed + * explanation. + */ + intel_batchbuffer_emit_mi_flush(brw); return; + } perf_debug("%s: fallback to CPU mapping in PBO case\n", __func__); } |