cpufreq: intel_pstate: Adjust the .adjust_perf() driver callback

In some cases, the processor may not actually stick to the "desired"
performance level programmed through the driver's .adjust_perf()
callback and may go above it, which may not be desirable (for instance,
there may be a UCLAMP_MAX limit set for the task currently running on
the given CPU which should be respected).

Address that by adjusting the .adjust_perf() callback to take an
additional argument, max_perf, representing the maximum allowed
performance level of the CPU and update the intel_pstate driver to
take that argument into account as appropriate.

Accordingly, adjust cpufreq_driver_adjust_perf() and the other existing
user of .adjust_perf(), which is the amd-pstate driver (but the behavior
of that driver is not changed).

While at it, also update the cpufreq_driver_adjust_perf()
documentation to reflect this change and some previous code
changes that have not been taken into account in it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Link: https://patch.msgid.link/6277654.lOV4Wx5bFT@rafael.j.wysocki
[ rjw: Adjusted Rust function formatting ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index a4e689eefdfb..7271cf24879d 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -50,6 +50,7 @@ struct sugov_cpu {
 
 	unsigned long		util;
 	unsigned long		bw_min;
+	unsigned long		bw_max;
 
 	/* The field below is for single-CPU policies only: */
 #ifdef CONFIG_NO_HZ_COMMON
@@ -232,6 +233,7 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu, unsigned long boost)
 	util = effective_cpu_util(sg_cpu->cpu, util, &min, &max);
 	util = max(util, boost);
 	sg_cpu->bw_min = min;
+	sg_cpu->bw_max = max;
 	sg_cpu->util = sugov_effective_cpu_perf(sg_cpu->cpu, util, min, max);
 }
 
@@ -484,7 +486,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
 		sg_cpu->util = prev_util;
 
 	cpufreq_driver_adjust_perf(sg_policy->policy, sg_cpu->bw_min,
-				   sg_cpu->util, max_cap);
+				   sg_cpu->util, sg_cpu->bw_max, max_cap);
 
 	sg_policy->need_freq_update = false;
 	sg_policy->last_freq_update_time = time;