Re: [Intel-gfx] [PATCH 3/3] drm/i915/pmu: Use common freq functions with sysfs

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Tue, 07 Mar 2023 22:12:49 -0800, Belgaumkar, Vinay wrote:
>

Hi Vinay,

> On 3/7/2023 9:33 PM, Ashutosh Dixit wrote:
> > Using common freq functions with sysfs in PMU (but without taking
> > forcewake) solves the following issues (a) missing support for MTL (b)
>
> For the requested_freq, we read it only if actual_freq is zero below
> (meaning, GT is in C6). So then what is the point of reading it without a
> force wake? It will also be zero, correct?

Yes agreed. I had tested this and you do see values for requested freq
which look correct even when actual freq is 0 even without taking
forcewake. That is why I ended up writing Patch 2/3.

However what I missed is what you pointed out that 0xa008 is a shadowed
register which cannot be read without taking forcewake. It is probably
returning the last value which was written to the shadowed write register.

As a result I have dropped the "drm/i915/rps: Expose
get_requested_frequency_fw for PMU" patch in v2 of this series.

Thanks.
--
Ashutosh