Comparing a blob trace using the feature to one not, the difference was pretty obvious and in the spot you'd expect compared to alphaToCoverage. The SP_ reg didn't have a corresponding bit set, though it also has an alphaToCoverage.
ac1ab9294ab turnip: Add support for alphaToOne.
src/freedreno/registers/a6xx.xml | 1 +
src/freedreno/vulkan/tu_device.c | 2 +-
src/freedreno/vulkan/tu_pipeline.c | 5 ++---
3 files changed, 4 insertions(+), 4 deletions(-)