Deadlocks with multiple applications on AMD RX460 - Updated

[Luís Mendes]

With the AMD RX460:
The commit 7aadd3abc1eedef97fc89adf6bf4602b224af890 - "drm/amdgpu: Fix
amdgpu_sync_add_later to preserve explicit flag" cherry picked into
drm-next-4.16 allows the glmark2 test to run until the end, otherwise
it will deadlock immediately at the start of glmark2 terrain test.
The tested mesa version is from the master branch at
commit5e1cb16768d3b97724ab85fbc50119dd8c9281c0 - "anv: fix a case
statement in GetMemoryFdPropertiesKHR".

Random deadlocks still occur at diverse occasions and with diverse
applications. The stack trace remains similar to the one reported in
the original email.

I've also tested an AMD R7 240 and it is producing system freezes
since several months ago up to the present moment, while playing
video, they are not deadlocks as the kernel completely freezes, not
just applications.

Regards,
Luis Mendes
Hardware and Software engineer