On Tue, Jun 6, 2017 at 11:00 PM, Chad Versace <c...@kiwitree.net> wrote:
> On Fri 26 May 2017, Jason Ekstrand wrote:
> > ---
> > src/mesa/drivers/dri/i965/brw_context.c | 55
> +++++----------------------
> > src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 55
> +++++++++++++++++++++++++++
> > src/mesa/drivers/dri/i965/intel_mipmap_tree.h | 6 +++
> > 3 files changed, 71 insertions(+), 45 deletions(-)
>
> > static void
> > intel_update_state(struct gl_context * ctx, GLuint new_state)
> > {
> > @@ -259,16 +224,16 @@ intel_update_state(struct gl_context * ctx, GLuint
> new_state)
> > /* We need inte_texture_object::_Format to be valid */
> > intel_finalize_mipmap_tree(brw, i);
> >
> > - if (intel_miptree_sample_with_hiz(brw, tex_obj->mt))
> > - intel_miptree_all_slices_resolve_hiz(brw, tex_obj->mt);
> > - else
> > - intel_miptree_all_slices_resolve_depth(brw, tex_obj->mt);
> > - /* Sampling engine understands lossless compression and resolving
> > - * those surfaces should be skipped for performance reasons.
> > - */
> > - const int flags = intel_texture_view_requires_resolve(brw,
> tex_obj) ?
> > - 0 : INTEL_MIPTREE_IGNORE_CCS_E;
> > - intel_miptree_all_slices_resolve_color(brw, tex_obj->mt, flags);
> > + bool aux_supported;
> > + intel_miptree_prepare_texture(brw, tex_obj->mt, tex_obj->_Format,
> > + &aux_supported);
> > +
> > + if (!aux_supported && brw->gen >= 9 &&
> > + intel_disable_rb_aux_buffer(brw, tex_obj->mt->bo)) {
> > + perf_debug("Sampling renderbuffer with non-compressible format
> - "
> > + "turning off compression");
> > + }
> > +
>
> I don't understand why intel_disable_rb_aux_buffer() is called here.
> Specifically, I don't understand why the code disables aux for
> a *framebuffer* attachment in response to the state of a *texture* view
> in the *same* draw call. There is hidden subtlety here.
>
> [time passes... tick tick tick]
>
> In general, the GL spec claims undefined behavior when simultaneuosly
> sampling and rendering to the same buffer. Self-blits are legal, though.
> So, it seems to me that intel_disable_rb_aux_buffer() is applicable here
> only during a glBlit* when src and dest are the same. Is that correct?
> Do there exist other applicable scenarios that I'm failing to see?
>
https://khronos.org/registry/OpenGL/extensions/ARB/ARB_texture_barrier.txt
> Anyway, this is just a refactoring patch, so
> Reviewed-by: Chad Versace <chadvers...@chromium.org>
>
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