linux-kernel - [PATCH v2 0/4] cpufreq: intel_pstate: Handle powersave governor correctly in the passive mode with HWP

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Date:   Mon, 09 Nov 2020 17:49:49 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Zhang Rui <rui.zhang@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Doug Smythies <dsmythies@...us.net>
Subject: [PATCH v2 0/4] cpufreq: intel_pstate: Handle powersave governor correctly in the passive mode with HWP

Hi,

Even after the changes made very recently, the handling of the powersave
governor is not exactly as expected when intel_pstate operates in the
"passive" mode with HWP enabled.

Namely, in that case HWP is not limited to the policy min frequency, but it
can scale the frequency up to the policy max limit and it cannot be constrained
currently, because there are no provisions for that in the framework.

To address that, patches [1-3/4] add a new governor flag to indicate that this
governor wants the target frequency to be set to the exact value passed to the
driver, if possible, and change the powersave and performance governors to have
that flag set.

The last patch makes intel_pstate take that flag into account when programming
the HWP Request MSR.

Thanks!