by Wyes Karny

[permalink] [raw]

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 <[email protected]>
>
> 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 <[email protected]>
> Tested-by: Wyes Karny <[email protected]>
> Reviewed-by: Mario Limonciello <[email protected]>
> Signed-off-by: Perry Yuan <[email protected]>
> ---
> 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 <[email protected]>

> +
> + 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