linux-kernel - RE: [RESEND PATCH V2 6/9] cpufreq: amd_pstate: add AMD pstate EPP support for shared memory type processor

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Date:   Thu, 20 Oct 2022 16:04:26 +0000
From:   "Yuan, Perry" <Perry.Yuan@....com>
To:     "Huang, Ray" <Ray.Huang@....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

[AMD Official Use Only - General]



> -----Original Message-----
> From: Huang, Ray <Ray.Huang@....com>
> Sent: Monday, October 17, 2022 6:55 PM
> To: Yuan, Perry <Perry.Yuan@....com>
> Cc: rafael.j.wysocki@...el.com; 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-
> 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

Do you mean that I could squash this patch into Patch 7 ?
If so , I will get this into V3. 

Perry.