[Intel-gfx] [PATCH] drm/i915: Delay the relase of the forcewake by a jiffie

[Daniel Vetter]

On Mon, Aug 26, 2013 at 01:46:09PM +0100, Chris Wilson wrote:
> Obtaining the forcwake requires expensive and time consuming
> serialisation. And we often try to obtain the forcewake multiple times
> in very quick succession. We can reduce the overhead of these sequences
> by delaying the forcewake release, and so not hammer the hw quite so
> hard.
> 
> I was hoping this would help with the spurious
> [drm:__gen6_gt_force_wake_mt_get] *ERROR* Timed out waiting for forcewake old ack to clear.
> found on Haswell. Alas not.
> 
> v2: Fix teardown ordering - unmap the regs after turning off forcewake,
> and make sure we do turn off forcewake - both found by Ville.
> 
> v3: As we introduce intel_uncore_fini(), use it to make sure everything
> is disabled before we hand back to the BIOS.
> 
> Note: I have no claims for improved performance, stablity or power
> comsumption for this patch. We should not be hitting the registers often
> enough for this to improve benchmarks, but given the nature of our hw it
> is likely to improve long term stability.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Queued for -next, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch