cpufreq: Pass policy pointer to ->update_limits()

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>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/8560367.NyiUUSuA9g@rjwysocki.net

Author: rafaeljw

drivers/cpufreq/amd-pstate.c

@@ -821,19 +821,16 @@ static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata)
 	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;
 

drivers/cpufreq/cpufreq.c

@@ -2769,7 +2769,7 @@ void cpufreq_update_limits(unsigned int cpu)
 		return;
 
 	if (cpufreq_driver->update_limits)
-		cpufreq_driver->update_limits(cpu);
+		cpufreq_driver->update_limits(policy);
 	else
 		cpufreq_policy_refresh(policy);
 }

drivers/cpufreq/intel_pstate.c

@@ -1353,14 +1353,9 @@ static void intel_pstate_update_policies(void)
 		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 @@ static bool intel_pstate_update_max_freq(struct cpudata *cpudata)
 			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];
 
-	if (intel_pstate_update_max_freq(cpudata))
-		hybrid_update_capacity(cpudata);
+	__intel_pstate_update_max_freq(policy, cpudata);
+
+	hybrid_update_capacity(cpudata);
 }
 
 static void intel_pstate_update_limits_for_all(void)

include/linux/cpufreq.h

@@ -399,7 +399,7 @@ struct cpufreq_driver {
 	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);