Re: [PATCH 12/14] cpufreq/amd-pstate: Cache a pointer to policy in cpudata
From: Dhananjay Ugwekar
Date: Tue Feb 11 2025 - 08:13:41 EST
On 2/7/2025 3:26 AM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@xxxxxxx>
>
> In order to access the policy from a notification block it will
> need to be stored in cpudata.
This might break the cpufreq_policy ref counting right?, if we cache the pointer
and use it independent of the ref counting framework.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> drivers/cpufreq/amd-pstate.c | 13 +++++++------
> drivers/cpufreq/amd-pstate.h | 3 ++-
> 2 files changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 689de385d06da..5945b6c7f7e56 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -388,7 +388,7 @@ static int amd_pstate_set_energy_pref_index(struct cpufreq_policy *policy,
> else
> epp = epp_values[pref_index];
>
> - if (epp > 0 && cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) {
> + if (epp > 0 && policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
> pr_debug("EPP cannot be set under performance policy\n");
> return -EBUSY;
> }
> @@ -689,7 +689,7 @@ static void amd_pstate_update_min_max_limit(struct cpufreq_policy *policy)
> perf.max_limit_perf = freq_to_perf(perf, cpudata->nominal_freq, policy->max);
> perf.min_limit_perf = freq_to_perf(perf, cpudata->nominal_freq, policy->min);
>
> - if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
> + if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
> perf.min_limit_perf = min(perf.nominal_perf, perf.max_limit_perf);
>
> WRITE_ONCE(cpudata->perf, perf);
> @@ -1042,6 +1042,7 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
> return -ENOMEM;
>
> cpudata->cpu = policy->cpu;
> + cpudata->policy = policy;
>
> mutex_init(&cpudata->lock);
> guard(mutex)(&cpudata->lock);
> @@ -1224,9 +1225,8 @@ static ssize_t show_energy_performance_available_preferences(
> {
> int i = 0;
> int offset = 0;
> - struct amd_cpudata *cpudata = policy->driver_data;
>
> - if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
> + if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
> return sysfs_emit_at(buf, offset, "%s\n",
> energy_perf_strings[EPP_INDEX_PERFORMANCE]);
>
> @@ -1543,6 +1543,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> return -ENOMEM;
>
> cpudata->cpu = policy->cpu;
> + cpudata->policy = policy;
>
> mutex_init(&cpudata->lock);
> guard(mutex)(&cpudata->lock);
> @@ -1632,7 +1633,7 @@ static int amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
>
> amd_pstate_update_min_max_limit(policy);
>
> - if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
> + if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
> epp = 0;
> else
> epp = READ_ONCE(cpudata->epp_cached);
> @@ -1651,7 +1652,7 @@ static int amd_pstate_epp_set_policy(struct cpufreq_policy *policy)
> if (!policy->cpuinfo.max_freq)
> return -ENODEV;
>
> - cpudata->policy = policy->policy;
> + cpudata->policy = policy;
>
> ret = amd_pstate_epp_update_limit(policy);
> if (ret)
> diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
> index 7501d30db9953..16ce631a6c3d5 100644
> --- a/drivers/cpufreq/amd-pstate.h
> +++ b/drivers/cpufreq/amd-pstate.h
> @@ -97,9 +97,10 @@ struct amd_cpudata {
>
> struct mutex lock;
>
> + struct cpufreq_policy *policy;
> +
> /* EPP feature related attributes*/
> u8 epp_cached;
> - u32 policy;
> bool suspended;
> u8 epp_default;
> };