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Message-ID: <Y000eLQY/nKqiNFZ@amd.com>
Date: Mon, 17 Oct 2022 18:54:48 +0800
From: Huang Rui <ray.huang@....com>
To: "Yuan, Perry" <Perry.Yuan@....com>
Cc: "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
"Sharma, Deepak" <Deepak.Sharma@....com>,
"Limonciello, Mario" <Mario.Limonciello@....com>,
"Fontenot, Nathan" <Nathan.Fontenot@....com>,
"Deucher, Alexander" <Alexander.Deucher@....com>,
"Huang, Shimmer" <Shimmer.Huang@....com>,
"Du, Xiaojian" <Xiaojian.Du@....com>,
"Meng, Li (Jassmine)" <Li.Meng@....com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH V2 6/9] cpufreq: amd_pstate: add AMD pstate EPP
support for shared memory type processor
On Tue, Oct 11, 2022 at 12:22:45AM +0800, Yuan, Perry wrote:
> Add Energy Performance Preference support for AMD SOCs which do not
> contain a designated MSR for CPPC support. A shared memory interface
> is used for CPPC on these SOCs and the ACPI PCC channel is used to
> enable EPP and reset the desired performance.
>
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> ---
> drivers/cpufreq/amd-pstate.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 2d28f458589c..08f9e335f97c 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -135,12 +135,25 @@ static inline int pstate_enable(bool enable)
>
> static int cppc_enable(bool enable)
> {
> + struct cppc_perf_ctrls perf_ctrls;
> int cpu, ret = 0;
>
> for_each_present_cpu(cpu) {
> ret = cppc_set_enable(cpu, enable);
> if (ret)
> return ret;
> + if (epp) {
> + /* Enable autonomous mode for EPP */
> + ret = cppc_set_auto_epp(cpu, enable);
> + if (ret)
> + return ret;
> +
> + /* Set desired perf as zero to allow EPP firmware control */
> + perf_ctrls.desired_perf = 0;
> + ret = cppc_set_perf(cpu, &perf_ctrls);
> + if (ret)
> + return ret;
> + }
This patch only writes the desired_perf as 0 to enable the EPP function,
but it cannot be an independent function or patch without the dependency of
the next one (patch 7).
Thanks,
Ray
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