[Mesa-dev] [PATCH 00/32] [v2] Renderbuffer Decompression (and GBM modifiers)

[Chad Versace]

This patch has a regressing side-effect: it disables CCS for all single-sample
miptrees created by glRenderbufferStorage(). After stepping through some Piglit
tests, I believe the problem is that line 161 below always returns false for
such miptrees because mt->is_scanout is true. I don't understand why
mt->is_scanout would be set for those miptrees.

The CCS gets disabled even if app never uses EGLImage nor modifiers.

    149 bool
    150 intel_miptree_supports_non_msrt_fast_clear(struct brw_context *brw,
    151                                            const struct intel_mipmap_tree *mt)
    152 {
    153    /* MCS support does not exist prior to Gen7 */
    154    if (brw->gen < 7)
    155       return false;
    156 
    157    if (mt->aux_disable & INTEL_AUX_DISABLE_MCS)
    158       return false;
    159 
    160    if (mt->is_scanout && mt->msaa_layout != INTEL_MSAA_LAYOUT_CMS)                  
  **161       return false;

That explains why 'egl_khr_gl_renderbuffer_image-clear-shared-image GL_RGBA'
passes on this patch series.