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SubjectRe: [PATCH 6/7] cpufreq: amd_pstate: implement amd pstate cpu online and offline callback
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On 9/9/2022 11:45, Perry Yuan wrote:
> The patch adds online and offline driver callback to 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.
>
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
> drivers/cpufreq/amd-pstate.c | 93 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 92 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index e71b06e20050..e63fed39f90c 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -111,7 +111,8 @@ struct amd_aperf_mperf {
> * @cppc_cap1_cached: Cached value of the last CPPC Capabilities MSR
> * @update_util: Cpufreq utility callback information
> * @sample: the stored performance sample
> -
> + * @suspended: Whether or not the driver has been suspended.
> + *
> * 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.
> */
> @@ -151,6 +152,7 @@ struct amd_cpudata {
> u64 cppc_cap1_cached;
> struct update_util_data update_util;
> struct amd_aperf_mperf sample;
> + bool suspended;
> };
>
> /**
> @@ -1387,6 +1389,93 @@ 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);

As this driver uses pr_fmt, this doesn't need to be as verbose. Look at
my comments in patch 7/7 and you can adopt the same here.

> +
> + 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 = all_cpu_data[policy->cpu];
> +
> + pr_debug("AMD CPU Core %d going online\n", cpudata->cpu);
> +
> + if (epp_enabled) {
> + amd_pstate_epp_reenable(cpudata);
> + cpudata->suspended = false;
> + }
> +
> + return 0;
> +}
> +
> +static void amd_pstate_epp_offline(struct cpufreq_policy *policy)
> +{
> + struct amd_cpudata *cpudata = all_cpu_data[policy->cpu];
> + 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(AMD_CPPC_EPP_POWERSAVE);
> + cppc_set_perf(cpudata->cpu, &perf_ctrls);
> + }
> + mutex_unlock(&amd_pstate_limits_lock);
> +}
> +
> +static int amd_pstate_cpu_offline(struct cpufreq_policy *policy)
> +{
> + struct amd_cpudata *cpudata = all_cpu_data[policy->cpu];
> +
> + pr_debug("AMD CPU Core %d going offline\n", cpudata->cpu); > +
> + if (cpudata->suspended)
> + return 0;
> +
> + if (epp_enabled)
> + amd_pstate_epp_offline(policy);
> +
> + return 0;
> +}
> +
> +static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
> +{
> + amd_pstate_clear_update_util_hook(policy->cpu);
> +
> + return amd_pstate_cpu_offline(policy);
> +}
> +
> static void amd_pstate_verify_cpu_policy(struct amd_cpudata *cpudata,
> struct cpufreq_policy_data *policy)
> {
> @@ -1421,6 +1510,8 @@ static struct cpufreq_driver amd_pstate_epp_driver = {
> .init = amd_pstate_epp_cpu_init,
> .exit = amd_pstate_epp_cpu_exit,
> .update_limits = amd_pstate_epp_update_limits,
> + .offline = amd_pstate_epp_cpu_offline,
> + .online = amd_pstate_epp_cpu_online,
> .name = "amd_pstate_epp",
> .attr = amd_pstate_epp_attr,
> };

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