[Intel-gfx] [PATCH 2/2 v2] drm/i915: catch gtfifo errors on forcewake_put

[Daniel Vetter]

On Sat, Feb 04, 2012 at 11:48:43AM -0800, Ben Widawsky wrote:
> This is similar to a patch I wrote several months ago. It's been updated
> for the new FORCEWAKE_MT, and it also no longer clears the debug
> register as it may be helpful to get that for the error state.  Also
> recommended by Chris Wilson, use WARN() instead of DRM_ERROR, so we can
> get a backtrace.
> 
> v2: replace POSTING_READ with I915_READ_NOTRACE(GTFIFODBG). Recommended
> by Chris Wilson
> 
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>

Looks good and because we can drop the posting read it shouldn't have any
perf impact. But we're not checking anything on the write side, which is
actually used the most under normal gem loads (tail updates). Because the
write path is rather perf critical, I think we should only check for
errors in the gt fifo reg if the wait_for_fifo times out. Can you whip up
that patch, too?

Thanks, Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48