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

[S, Deepak]

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.