[Intel-gfx] [PATCH] [CFT] drm/i915: Only set the down rps limit when at the loweset frequency

[Chris Wilson]

On Wed, 25 Jul 2012 21:32:09 +0200, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> The power docs say that when the gt leaves rc6, it is in the lowest
> frequency and only about 25 usec later will switch to the frequency
> selected in GEN6_RPNSWREQ. If the downclock limit expires in that
> window and the down limit is set to the lowest possible frequency, the
> hw will not send the down interrupt. Which leads to a too high gpu
> clock and wasted power.
> 
> Chris Wilson already worked on this with
> 
> commit 7b9e0ae6da0a7eaf2680a1a788f08df123724f3b
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Sat Apr 28 08:56:39 2012 +0100
> 
>     drm/i915: Always update RPS interrupts thresholds along with
>     frequency
> 
> but got the logic inverted: The current code set the down limit as
> long as we haven't reached it. Instead of only once with reached the
> lowest frequency.

Yup, that's different to the opposite of what I thought I was writing to
comply with the guide. :(

Note you also have to fix up intel_sanitize_pm().
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre