[Intel-gfx] [PATCH v2] drm/i915: recheck ringspace after wait+retire

[Chris Wilson]

On Thu, Dec 18, 2014 at 05:03:41PM +0000, Dave Gordon wrote:
> In {intel,logical}_ring_wait_request(), we try to find a request
> whose completion will release the amount of ring space required.
> If we find such a request, we wait for it, and then retire it, in
> the expectation that we will now have at least the required amount
> of free space in the ring. But it's good to check that this has
> actually happened, so we can back out with a meaningful error
> code if something unexpected has happened, such as wait_request
> returning early.

It's pretty pointless. It's a programming bug, if anything it should
WARN if it happens.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre