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Subject: Re: [PATCH V3 0/4] cpufreq: cppc: Add support for frequency
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To:     Ionela Voinescu <ionela.voinescu@arm.com>
CC:     Vincent Guittot <vincent.guittot@linaro.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Rafael Wysocki <rjw@rjwysocki.net>,
        Ben Segall <bsegall@google.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Mel Gorman <mgorman@suse.de>,
        Peter Zijlstra <peterz@infradead.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Will Deacon <will@kernel.org>,
        "open list:THERMAL" <linux-pm@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
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From:   Qian Cai <quic_qiancai@quicinc.com>
Message-ID: <253b765a-c152-4640-36cc-09d873d029c4@quicinc.com>
Date:   Tue, 29 Jun 2021 09:38:21 -0400
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On 6/29/2021 5:06 AM, Ionela Voinescu wrote:
>> Ionela, I found that set ACPI_PROCESSOR=y instead of ACPI_PROCESSOR=m
>> will fix the previous mentioned issues here (any explanations of that?)
>> even though the scaling down is not perfect. Now, we have the following
>> on this idle system:
>>
> 
> I don't see how this would have played a role. The cppc cpufreq driver
> depends on functionality gated by CONFIG_ACPI_CPPC_LIB which in turn
> needs CONFIG_ACPI_PROCESSOR to trigger the parsing of the _CPC objects.
> If CONFIG_ACPI_PROCESSOR functionality is not built in or loaded, the
> cppc cpufreq driver could not be used at all.

Ionela, that is fine. I can live with setting ACPI_PROCESSOR=y to workaround. I
was more of just curious about why manually loading processor.ko would set the
lowest to 2GHz instead of 1GHz.

Anyway, if running below the lowest is not the a concern, then I have concluded
my testing here. Feel free to include:

Tested-by: Qian Cai <quic_qiancai@quicinc.com>