looks like the benchmark needs more than the allocated 10s to complete. you can
adjust this via radeon.lockup_timeout kernel module parameter.
You can check the used value at:
/sys/module/radeon/parameters/lockup_timeout
but you'll need to set it at boot time.

(In reply to Ricardo Ribalda from comment #0)
> 
> real	20m10.785s
> user	15m58.717s
> sys	1m5.031s

oh, that's pretty slow...