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:   Tue, 25 Oct 2022 08:25:41 +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 Fri, Oct 21, 2022 at 12:04:26AM +0800, Yuan, Perry wrote:
> [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. 
> 

Yes, thanks.

Ray