<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Oct 6, 2017 at 11:13 AM, Nanley Chery <<a href="mailto:nanleychery@gmail.com" target="_blank">nanleychery@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">On Thu, Oct 05, 2017 at 10:02:40PM -0700, Kenneth Graunke wrote: > Jason and I investigated several OpenGL CTS failures where the tests > bind the same texture for rendering and texturing, at the same time. > This has defined results as long as the reads happen before writes, > or the regions are non-overlapping. Normally, this just works out. > > However, CCS can cause problems. If the shader is reading one set of > pixels, and writing to different pixels that are adjacent, they may end > up being covered by the same CCS block. So rendering may be writing a > CCS block, while the sampler is trying to read it. Corruption ensues. > > Disabling CCS is unfortunate, but safe. > > Fixes several KHR-GL45.texture_barrier.* subtests. > > Cc: <a href="mailto:nanleychery@gmail.com">nanleychery@gmail.com</a> > Cc: <a href="mailto:jason@jlekstrand.net">jason@jlekstrand.net</a> > --- > src/mesa/drivers/dri/i965/brw_draw.c | 8 +++++++- > src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 13 +++++++------ > src/mesa/drivers/dri/i965/intel_mipmap_tree.h | 2 +- > 3 files changed, 15 insertions(+), 8 deletions(-) > > diff --git a/src/mesa/drivers/dri/i965/brw_draw.c b/src/mesa/drivers/dri/i965/brw_draw.c > index cab3758d7b5..c13fa8c367a 100644 > --- a/src/mesa/drivers/dri/i965/brw_draw.c > +++ b/src/mesa/drivers/dri/i965/brw_draw.c > @@ -383,7 +383,13 @@ brw_predraw_resolve_inputs(struct brw_context *brw) > translate_tex_format(brw, tex_obj->_Format, sampler->sRGBDecode); > int drawbuf_idx = get_drawbuffer_index(brw, tex_obj->mt->bo); > > - bool aux_supported; > + /* Disable auxiliary buffers if there's a self-dependency, where > + * we're both texturing from and rendering to the same buffer. > + * It's not necessarily safe - concurrent reads and writes to the > + * CCS buffer can result in incorrect pixels. > + */ > + bool aux_supported = drawbuf_idx == -1; > + > intel_miptree_prepare_texture(brw, tex_obj->mt, view_format, > &aux_supported); > > diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c > index 5b7cde82f65..29b93dd656c 100644 > --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c > +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c > @@ -2651,9 +2651,10 @@ intel_miptree_prepare_texture_slices(struct brw_context *brw, > enum isl_format view_format, > uint32_t start_level, uint32_t num_levels, > uint32_t start_layer, uint32_t num_layers, > - bool *aux_supported_out) > + bool *aux_supported) </div></div>I find the name of this new parameter a little misleading. It suggests that the caller can determine that the aux surface is usable during the texture operation, when in fact it is the intel_miptree_texture_aux_usage function in the callee which does this determination. Since the caller can determine that the aux surface cannot be used, perhaps something like disable_aux would be a better fit? </blockquote><div> </div><div>I was thinking the same thing. </div></div></div></div>