linux-kernel - RE: [PATCH v9 06/13] cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors

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Date:   Fri, 6 Jan 2023 05:58:40 +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 v9 06/13] cpufreq: amd-pstate: implement Pstate EPP
 support for the AMD processors

[AMD Official Use Only - General]

Hi Wyes. 

> -----Original Message-----
> From: Karny, Wyes <Wyes.Karny@....com>
> Sent: Friday, January 6, 2023 1:22 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 v9 06/13] cpufreq: amd-pstate: implement Pstate EPP
> support for the AMD processors
> 
> Hi Perry,
> 
> On 12/25/2022 10:04 PM, Perry Yuan wrote:
> ----------------------------------->8-------------------------------
> > +static struct cpufreq_driver amd_pstate_epp_driver = {
> > +	.flags		= CPUFREQ_CONST_LOOPS,
> > +	.verify		= amd_pstate_epp_verify_policy,
> > +	.setpolicy	= amd_pstate_epp_set_policy,
> > +	.init		= amd_pstate_epp_cpu_init,
> > +	.exit		= amd_pstate_epp_cpu_exit,
> > +	.name		= "amd_pstate_epp",
> 
> Small nit, amd_pstate_driver name is "amd-pstate", whereas here for
> amd_pstate_epp_driver name "amd_pstate_epp" is used.
> Should amd_pstate_driver renamed "amd_pstate"?

For the non-epp and epp driver name, I suggest to keep the same rule for the name. but it depends on Ray would like to change it or not for non-epp driver name.


> 
> > +	.attr		= amd_pstate_epp_attr,
> > +};
> > +
> >  static int __init amd_pstate_init(void)  {
> >  	int ret;
> > @@ -656,7 +1012,8 @@ static int __init amd_pstate_init(void)
> >  	/* capability check */
> >  	if (boot_cpu_has(X86_FEATURE_CPPC)) {
> >  		pr_debug("AMD CPPC MSR based functionality is
> supported\n");
> > -		amd_pstate_driver.adjust_perf = amd_pstate_adjust_perf;
> > +		if (cppc_state == AMD_PSTATE_PASSIVE)
> > +			default_pstate_driver->adjust_perf =
> amd_pstate_adjust_perf;
> >  	} else {
> >  		pr_debug("AMD CPPC shared memory based functionality is
> supported\n");
> >  		static_call_update(amd_pstate_enable, cppc_enable); @@ -
> 667,14
> > +1024,13 @@ static int __init amd_pstate_init(void)
> >  	/* enable amd pstate feature */
> >  	ret = amd_pstate_enable(true);
> >  	if (ret) {
> > -		pr_err("failed to enable amd-pstate with return %d\n", ret);
> > +		pr_err("failed to enable with return %d\n", ret);
> >  		return ret;
> >  	}
> >
> > -	ret = cpufreq_register_driver(&amd_pstate_driver);
> > +	ret = cpufreq_register_driver(default_pstate_driver);
> >  	if (ret)
> > -		pr_err("failed to register amd_pstate_driver with
> return %d\n",
> > -		       ret);
> > +		pr_err("failed to register with return %d\n", ret);
> >
> >  	return ret;
> >  }
> > @@ -696,6 +1052,12 @@ static int __init amd_pstate_param(char *str)
> >  		if (cppc_state == AMD_PSTATE_DISABLE)
> >  			pr_info("driver is explicitly disabled\n");
> >
> > +		if (cppc_state == AMD_PSTATE_ACTIVE)
> > +			default_pstate_driver = &amd_pstate_epp_driver;
> > +
> > +		if (cppc_state == AMD_PSTATE_PASSIVE)
> > +			default_pstate_driver = &amd_pstate_driver;
> > +
> >  		return 0;
> >  	}
> >
> > diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> > index dae2ce0f6735..8341a2a2948a 100644
> > --- a/include/linux/amd-pstate.h
> > +++ b/include/linux/amd-pstate.h
> > @@ -47,6 +47,10 @@ struct amd_aperf_mperf {
> >   * @prev: Last Aperf/Mperf/tsc count value read from register
> >   * @freq: current cpu frequency value
> >   * @boost_supported: check whether the Processor or SBIOS supports
> > boost mode
> > + * @epp_policy: Last saved policy used to set energy-performance
> > + preference
> > + * @epp_cached: Cached CPPC energy-performance preference value
> > + * @policy: Cpufreq policy value
> > + * @cppc_cap1_cached Cached MSR_AMD_CPPC_CAP1 register value
> >   *
> >   * The amd_cpudata is key private data for each CPU thread in AMD P-
> State, and
> >   * represents all the attributes and goals that AMD P-State requests at
> runtime.
> > @@ -72,6 +76,12 @@ struct amd_cpudata {
> >
> >  	u64	freq;
> >  	bool	boost_supported;
> > +
> > +	/* EPP feature related attributes*/
> > +	s16	epp_policy;
> > +	s16	epp_cached;
> > +	u32	policy;
> > +	u64	cppc_cap1_cached;
> >  };
> >
> >  /*
> 
> --
> Thanks & Regards,
> Wyes