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Message-ID: <DM4PR12MB5278668BD034D950AB7416AB9C099@DM4PR12MB5278.namprd12.prod.outlook.com>
Date: Fri, 18 Nov 2022 03:54:29 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: "Karny, Wyes" <Wyes.Karny@....com>,
"rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
"Limonciello, Mario" <Mario.Limonciello@....com>,
"Huang, Ray" <Ray.Huang@....com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>
CC: "Sharma, Deepak" <Deepak.Sharma@....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: [PATCH v4 4/9] cpufreq: amd_pstate: implement Pstate EPP support
for the AMD processors
[AMD Official Use Only - General]
> -----Original Message-----
> From: Karny, Wyes <Wyes.Karny@....com>
> Sent: Thursday, November 17, 2022 10:03 PM
> To: Yuan, Perry <Perry.Yuan@....com>; rafael.j.wysocki@...el.com;
> Limonciello, Mario <Mario.Limonciello@....com>; Huang, Ray
> <Ray.Huang@....com>; viresh.kumar@...aro.org
> Cc: Sharma, Deepak <Deepak.Sharma@....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-
> kernel@...r.kernel.org
> Subject: Re: [PATCH v4 4/9] cpufreq: amd_pstate: implement Pstate EPP support
> for the AMD processors
>
> Hi Perry,
>
> On 11/10/2022 11:28 PM, Perry Yuan wrote:
> [snip]
> > +
> > +static ssize_t store_energy_performance_preference(
> > + struct cpufreq_policy *policy, const char *buf, size_t count) {
> > + struct amd_cpudata *cpudata = policy->driver_data;
> > + char str_preference[21];
> > + ssize_t ret;
> > + u32 epp = 0;
>
> Here `epp` is a unused variable.
> [snip]
> > @@ -657,6 +1281,20 @@ static int __init amd_pstate_param(char *str)
> > if (!str)
> > return -EINVAL;
> >
> > + /*
> > + * Disable amd-pstate driver by default for now
> > + * append amd-pstate=active or amd-pstate=active
> > + * to enable driver loaded
> > + */
> > + if (!strcmp(str, "active")) {
> > + cppc_load = 1;
> > + default_pstate_driver = &amd_pstate_epp_driver;
> > + } else if (!strcmp(str, "passive")) {
> > + epp_off = 1;
> > + cppc_load = 1;
> > + default_pstate_driver = &amd_pstate_driver;
> > + }
> > +
> > /*
> > * support shared memory type CPPC which has no MSR function.
> > * enable amd-pstate on processors with shared memory solution
>
> In the shared memory support section also `cppc_load` has to be set otherwise
> amd_pstate=legacy_cppc will not work.
If the patches just got reviewed are accepted, the legacy_cppcc will not be needed any more.
I will rebase the EPP patches based on the that.
>
> if (!strcmp(str, "legacy_cppc")) {
> shared_mem = true;
> cppc_load = 1;
> }
Previous plan was to add two parameters to kernel command line,
passive or active and legacy_cppc for shared memory platform.
>
>
> --
> Thanks & Regards,
> Wyes
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