34010a50d4
The lock and condition variable isn't just for present_id anymore, it's also for normal forward progress. Adds more detailed comments what the variables are supposed to accomplish. Signed-off-by: Hans-Kristian Arntzen <post@arntzen-software.no> Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19990>