[Intel-gfx] [PATCH v2 3/3] drm/i915/vlv: WA for Turbo and RC6 to work together.

[Jesse Barnes]

On Wed, 22 Jan 2014 22:07:53 +0530
"S, Deepak" <deepak.s at intel.com> wrote:

> 
> 
> On 1/22/2014 10:04 PM, Jesse Barnes wrote:
> > On Tue, 21 Jan 2014 17:18:59 +0200
> > Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> >
> >> On Mon, Jan 20, 2014 at 06:40:26PM +0530, deepak.s at intel.com wrote:
> >>> From: Deepak S <deepak.s at intel.com>
> >>>
> >>> With RC6 enabled, BYT has an HW issue in determining the right
> >>> Gfx busyness.
> >>> WA for Turbo + RC6: Use SW based Gfx busy-ness detection to decide
> >>> on increasing/decreasing the freq. This logic will monitor C0
> >>> counters of render/media power-wells over EI period and takes
> >>> necessary action based on these values
> >>
> >> Do we have any idea what kind of performance impact this should
> >> have?
> >
> > So aside from the code review comments, it sounds like there are two
> > high level issues:
> >    1) keeping existing boost code from Chris (as mentioned by Ville)
> >    2) power measurements vs current upstream
> >
> > Given that upstream is a bit different than when this code was forked
> > off, it could be that we don't need this.  Can you sanity check things
> > by getting some power measurements with and without this patch?  It
> > looks like 1/3 and 2/3 will be required in any case though.
> >
> > Assuming 3/3 does show a benefit, the other question is whether keeping
> > the current turbo boost code makes sense, so you'd have to port those
> > changes from the gen6_pm_rps_work() from Chris and measure again...
> >
> > Thanks,
> >
> 
> Sure Jesse, I will do power measurement and get back to you on the results.

Great, thanks Deepak.  And this mail looks a lot nicer. :)  Thunderbird
definitely molests mail less readily than Outlook.

--
Jesse Barnes, Intel Open Source Technology Center