Christian Duerr authored Dec 03, 2023 and Marge Bot committed Feb 05, 2024

If dual blending is enabled, only 1 output is supported. Multiple
outputs confuse the write combining pass in this case, leading to
incorrect output and/or an assert failure in emit_fragment_store.

The fix is straightforward, just skip the speculative emitting of
multiple outputs in the case where dual source blending is enabled.

This also adds an extra sanity check in `pan_nir_lower_zs_store` to
check for only one blend store being present.

Fixes: c65a9be4 ("panfrost: Preprocess shaders at CSO create time")
Closes: mesa/mesa#9487


Co-Authored-By: Eric R. Smith <eric.smith@collabora.com>
Part-of: <mesa/mesa!26474>