Re: [PATCH v1 10/10] cpufreq: Pass policy pointer to ->update_limits()

Rafael J. Wysocki
2025-04-07T18:48:39Z

On Fri, Mar 28, 2025 at 9:49 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Since cpufreq_update_limits() obtains a cpufreq policy pointer for the
> given CPU and reference counts the corresponding policy object, it may
> as well pass the policy pointer to the cpufreq driver's ->update_limits()
> callback which allows that callback to avoid invoking cpufreq_cpu_get()
> for the same CPU.
>
> Accordingly, redefine ->update_limits() to take a policy pointer instead
> of a CPU number and update both drivers implementing it, intel_pstate
> and amd-pstate, as needed.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Hi Srinivas,

If you have any concerns regarding this patch, please let me know
(note that it is based on the [05/10]).

> ---
> drivers/cpufreq/amd-pstate.c | 7 ++-----
> drivers/cpufreq/cpufreq.c | 2 +-
> drivers/cpufreq/intel_pstate.c | 29 ++++++++++++++++++-----------
> include/linux/cpufreq.h | 2 +-
> 4 files changed, 22 insertions(+), 18 deletions(-)
>
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -821,19 +821,16 @@
> schedule_work(&sched_prefcore_work);
> }
>
> -static void amd_pstate_update_limits(unsigned int cpu)
> +static void amd_pstate_update_limits(struct cpufreq_policy *policy)
> {
> - struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
> struct amd_cpudata *cpudata;
> u32 prev_high = 0, cur_high = 0;
> bool highest_perf_changed = false;
> + unsigned int cpu = policy->cpu;
>
> if (!amd_pstate_prefcore)
> return;
>
> - if (!policy)
> - return;
> -
> if (amd_get_highest_perf(cpu, &cur_high))
> return;
>
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2741,7 +2741,7 @@
> return;
>
> if (cpufreq_driver->update_limits)
> - cpufreq_driver->update_limits(cpu);
> + cpufreq_driver->update_limits(policy);
> else
> cpufreq_policy_refresh(policy);
> }
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -1353,14 +1353,9 @@
> cpufreq_update_policy(cpu);
> }
>
> -static bool intel_pstate_update_max_freq(struct cpudata *cpudata)
> +static void __intel_pstate_update_max_freq(struct cpufreq_policy *policy,
> + struct cpudata *cpudata)
> {
> - struct cpufreq_policy *policy __free(put_cpufreq_policy);
> -
> - policy = cpufreq_cpu_get(cpudata->cpu);
> - if (!policy)
> - return false;
> -
> guard(cpufreq_policy_write)(policy);
>
> if (hwp_active)
> @@ -1370,16 +1365,28 @@
> cpudata->pstate.max_freq : cpudata->pstate.turbo_freq;
>
> refresh_frequency_limits(policy);
> +}
> +
> +static bool intel_pstate_update_max_freq(struct cpudata *cpudata)
> +{
> + struct cpufreq_policy *policy __free(put_cpufreq_policy);
> +
> + policy = cpufreq_cpu_get(cpudata->cpu);
> + if (!policy)
> + return false;
> +
> + __intel_pstate_update_max_freq(policy, cpudata);
>
> return true;
> }
>
> -static void intel_pstate_update_limits(unsigned int cpu)
> +static void intel_pstate_update_limits(struct cpufreq_policy *policy)
> {
> - struct cpudata *cpudata = all_cpu_data[cpu];
> + struct cpudata *cpudata = all_cpu_data[policy->cpu];
> +
> + __intel_pstate_update_max_freq(policy, cpudata);
>
> - if (intel_pstate_update_max_freq(cpudata))
> - hybrid_update_capacity(cpudata);
> + hybrid_update_capacity(cpudata);
> }
>
> static void intel_pstate_update_limits_for_all(void)
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -399,7 +399,7 @@
> unsigned int (*get)(unsigned int cpu);
>
> /* Called to update policy limits on firmware notifications. */
> - void (*update_limits)(unsigned int cpu);
> + void (*update_limits)(struct cpufreq_policy *policy);
>
> /* optional */
> int (*bios_limit)(int cpu, unsigned int *limit);
>
>
>
>