linux-kernel - Re: [PATCH v4] cpufreq / CPPC: Add cpuinfo_cur

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Date:   Fri, 13 Jul 2018 16:20:43 -0600
From:   "Prakash, Prashanth" <pprakash@...eaurora.org>
To:     George Cherian <george.cherian@...ium.com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     viresh.kumar@...aro.org, rjw@...ysocki.net
Subject: Re: [PATCH v4] cpufreq / CPPC: Add cpuinfo_cur_freq support for CPPC

Hi George,

This version looks good. Thanks!

On 7/12/2018 12:07 AM, George Cherian wrote:
> Per Section 8.4.7.1.3 of ACPI 6.2, The platform provides performance
> feedback via set of performance counters. To determine the actual
> performance level delivered over time, OSPM may read a set of
> performance counters from the Reference Performance Counter Register
> and the Delivered Performance Counter Register.
>
> OSPM calculates the delivered performance over a given time period by
> taking a beginning and ending snapshot of both the reference and
> delivered performance counters, and calculating:
>
> delivered_perf = reference_perf X (delta of delivered_perf counter / delta of reference_perf counter).
>
> Implement the above and hook this to the cpufreq->get method.
>
> Signed-off-by: George Cherian <george.cherian@...ium.com>
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Acked-by: Prashanth Prakash <pprakash@...eaurora.org>