Re: [PATCH v2 1/2] arch_topology: seed capacity_freq_ref with boost-aware max freq

capacity_freq_ref, the per-CPU frequency-invariance reference used by
schedutil, is seeded from policy->cpuinfo.max_freq at policy creation.
If boost frequencies are filtered out of the frequency table because
boost isn't yet enabled at boot, max_freq only reflects the non-boost
ceiling, so capacity_freq_ref never learns about boost frequencies for
the policy's lifetime. Enabling boost later raises policy->max, but
capacity_freq_ref stays stale, leaving schedutil unable to scale
utilization or target a frequency above the non-boost maximum.

Track the highest frequency in the table regardless of boost state
(max_table_freq) and seed capacity_freq_ref with max(cpuinfo.max_freq,
max_table_freq), so the invariance reference is boost-aware from boot
regardless of whether boost is currently enabled. Runtime enforcement,
still handled by policy->max, is unaffected.

Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ananthu C V <redacted>
---
 drivers/base/arch_topology.c | 3 ++-
 drivers/cpufreq/freq_table.c | 6 ++++++
 include/linux/cpufreq.h      | 1 +
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 8c5e47c28d9a..da94f77441da 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c

@@ -404,7 +404,8 @@ init_cpu_capacity_callback(struct notifier_block *nb,
        cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);

        for_each_cpu(cpu, policy->related_cpus) {
-               per_cpu(capacity_freq_ref, cpu) = policy->cpuinfo.max_freq;
+               per_cpu(capacity_freq_ref, cpu) = max(policy->cpuinfo.max_freq,
+                                                     policy->cpuinfo.max_table_freq);

                freq_inv_set_max_ratio(cpu,
                                       per_cpu(capacity_freq_ref, cpu) * HZ_PER_KHZ);
        }

diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index ea994647abc8..4984142dc08a 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c

@@ -33,11 +33,15 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
        struct cpufreq_frequency_table *pos, *table = policy->freq_table;
        unsigned int min_freq = ~0;
        unsigned int max_freq = 0;
+       unsigned int max_table_freq = 0;
        unsigned int freq, i;

        cpufreq_for_each_valid_entry_idx(pos, table, i) {
                freq = pos->frequency;

+               if (freq > max_table_freq)
+                       max_table_freq = freq;
+
                if ((!cpufreq_boost_enabled() || !policy->boost_enabled)
                    && (pos->flags & CPUFREQ_BOOST_FREQ))
                        continue;

@@ -57,6 +61,8 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
        if (policy->cpuinfo.max_freq < max_freq)
                policy->cpuinfo.max_freq = max_freq;

+       policy->cpuinfo.max_table_freq = max_table_freq;
+
        if (min_freq == ~0)
                return -EINVAL;
        else

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 35ce665edfd8..3f3b1380251a 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h

@@ -45,6 +45,7 @@ enum cpufreq_table_sorting {
 struct cpufreq_cpuinfo {
        unsigned int            max_freq;
        unsigned int            min_freq;
+       unsigned int            max_table_freq; /* Highest valid frequency in the table */

        /* in 10^(-9) s = nanoseconds */
        unsigned int            transition_latency;

--