If a user mode driver is changed to rely on the existence of implicit sync, it results in corruption and flickering as reported here: https://gitlab.freedesktop.org/mesa/mesa/-/issues/2950

Marek

On Mon, May 25, 2020 at 6:05 PM Marek Olšák <maraeo@gmail.com> wrote:
Hi Christian,

Bas and Michel wanted to discuss this. The main disadvantage of no implicit (pipeline) sync within the same queue is that we get lower performance and lower GPU utilization in some cases.

We actually never really needed the kernel to have implicit sync, because all user mode drivers contained hacks to work without it.

Marek