linux-kernel - Re: [PATCH v11 05/11] cpufreq: amd-pstate: implement amd pstate cpu online and offline callback

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Message-ID: <50040e9d-0d8a-e101-1332-542c7b564c99@amd.com>
Date:   Thu, 19 Jan 2023 10:57:43 +0530
From:   Wyes Karny <wyes.karny@....com>
To:     Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
        Mario.Limonciello@....com, ray.huang@....com,
        viresh.kumar@...aro.org
Cc:     Deepak.Sharma@....com, Nathan.Fontenot@....com,
        Alexander.Deucher@....com, Shimmer.Huang@....com,
        Xiaojian.Du@....com, Li.Meng@....com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v11 05/11] cpufreq: amd-pstate: implement amd pstate cpu
 online and offline callback



On 1/18/2023 1:22 PM, Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@....com>
> 
> Adds online and offline driver callback support to allow cpu cores go
> offline and help to restore the previous working states when core goes
> back online later for EPP driver mode.
> 
> Acked-by: Huang Rui <ray.huang@....com>
> Tested-by: Wyes Karny <wyes.karny@....com>
> Reviewed-by: Mario Limonciello <Mario.Limonciello@....com>
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 82 ++++++++++++++++++++++++++++++++++++
>  include/linux/amd-pstate.h   |  1 +
>  2 files changed, 83 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 2109ad3fdd42..1472a6382b29 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -958,6 +958,86 @@ static int amd_pstate_epp_set_policy(struct cpufreq_policy *policy)
>  	return 0;
>  }
>  
> +static void amd_pstate_epp_reenable(struct amd_cpudata *cpudata)
> +{
> +	struct cppc_perf_ctrls perf_ctrls;
> +	u64 value, max_perf;
> +	int ret;
> +
> +	ret = amd_pstate_enable(true);
> +	if (ret)
> +		pr_err("failed to enable amd pstate during resume, return %d\n", ret);
> +
> +	value = READ_ONCE(cpudata->cppc_req_cached);
> +	max_perf = READ_ONCE(cpudata->highest_perf);
> +
> +	if (boot_cpu_has(X86_FEATURE_CPPC)) {
> +		wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, value);
> +	} else {
> +		perf_ctrls.max_perf = max_perf;
> +		perf_ctrls.energy_perf = AMD_CPPC_ENERGY_PERF_PREF(cpudata->epp_cached);
> +		cppc_set_perf(cpudata->cpu, &perf_ctrls);
> +	}
> +}
> +
> +static int amd_pstate_epp_cpu_online(struct cpufreq_policy *policy)
> +{
> +	struct amd_cpudata *cpudata = policy->driver_data;
> +
> +	pr_debug("AMD CPU Core %d going online\n", cpudata->cpu);
> +
> +	if (cppc_state == AMD_PSTATE_ACTIVE) {
> +		amd_pstate_epp_reenable(cpudata);
> +		cpudata->suspended = false;
> +	}
> +
> +	return 0;
> +}
> +
> +static void amd_pstate_epp_offline(struct cpufreq_policy *policy)
> +{
> +	struct amd_cpudata *cpudata = policy->driver_data;
> +	struct cppc_perf_ctrls perf_ctrls;
> +	int min_perf;
> +	u64 value;
> +
> +	min_perf = READ_ONCE(cpudata->lowest_perf);
> +	value = READ_ONCE(cpudata->cppc_req_cached);
> +
> +	mutex_lock(&amd_pstate_limits_lock);
> +	if (boot_cpu_has(X86_FEATURE_CPPC)) {
> +		cpudata->epp_policy = CPUFREQ_POLICY_UNKNOWN;
> +
> +		/* Set max perf same as min perf */
> +		value &= ~AMD_CPPC_MAX_PERF(~0L);
> +		value |= AMD_CPPC_MAX_PERF(min_perf);
> +		value &= ~AMD_CPPC_MIN_PERF(~0L);
> +		value |= AMD_CPPC_MIN_PERF(min_perf);
> +		wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, value);
> +	} else {
> +		perf_ctrls.desired_perf = 0;
> +		perf_ctrls.max_perf = min_perf;
> +		perf_ctrls.energy_perf = AMD_CPPC_ENERGY_PERF_PREF(HWP_EPP_BALANCE_POWERSAVE);
> +		cppc_set_perf(cpudata->cpu, &perf_ctrls);
> +	}
> +	mutex_unlock(&amd_pstate_limits_lock);
> +}
> +
> +static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
> +{
> +	struct amd_cpudata *cpudata = policy->driver_data;
> +
> +	pr_debug("AMD CPU Core %d going offline\n", cpudata->cpu);
> +
> +	if (cpudata->suspended)
> +		return 0;
> +
> +	if (cppc_state == AMD_PSTATE_ACTIVE)
> +		amd_pstate_epp_offline(policy);

Should we call `amd_pstate_enable(false)` here?

With this:
Reviewed-by: Wyes Karny <wyes.karny@....com>

> +
> +	return 0;
> +}
> +
>  static int amd_pstate_epp_verify_policy(struct cpufreq_policy_data *policy)
>  {
>  	cpufreq_verify_within_cpu_limits(policy);
> @@ -984,6 +1064,8 @@ static struct cpufreq_driver amd_pstate_epp_driver = {
>  	.setpolicy	= amd_pstate_epp_set_policy,
>  	.init		= amd_pstate_epp_cpu_init,
>  	.exit		= amd_pstate_epp_cpu_exit,
> +	.offline	= amd_pstate_epp_cpu_offline,
> +	.online		= amd_pstate_epp_cpu_online,
>  	.name		= "amd_pstate_epp",
>  	.attr		= amd_pstate_epp_attr,
>  };
> diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> index 9bfdabd9d930..e9e291b7c2f9 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -82,6 +82,7 @@ struct amd_cpudata {
>  	s16	epp_cached;
>  	u32	policy;
>  	u64	cppc_cap1_cached;
> +	bool	suspended;
>  };
>  
>  /*

-- 
Thanks & Regards,
Wyes