[PATCH 12/13] drm/radeon: fix a bug with the ring syncing code

[Christian König]

On 24.04.2012 16:04, Dave Airlie wrote:
> 2012/4/19 Christian König<deathsimple at vodafone.de>:
>> Rings need to lock in order, otherwise
>> the ring subsystem can deadlock.
> No sure if its the commit or not but I was profiling on an r700 and
> saw it create a semaphore for ring syncing.
>
> surely the r700 would have no need?
>
In theory the first hardware with more than a gfx ring was some r6xx 
(but of course we haven't released any code/documentation for that yet), 
so it's ok that the code generally checks for inter ring synchronization 
needs on r7xx cards.

But with the current mainline it should just boil down to an not taken 
"if" branch, witch it currently doesn't (*crap*). Just tested with my 
RV710 and I can confirm that it unnecessarily allocates a semaphore. 
Another bug on my todo list for this patchset, going to send out an v2 
soon, but going to test it through first.

Thanks for the comment,
Christian.