[PATCH 2/2] sched/cpufreq: Update schedutil's DVFS request to reach the boost frequencies

[Sibi Sankar <sibi.sankar@oss.qualcomm.com>]

capacity_freq_ref, exposed to schedutil via get_capacity_ref_freq(),
was introduced by commit 9942cb22ea45 ("sched/topology: Add a new
arch_scale_freq_ref() method") as a fixed anchor that does not move at
runtime. However, schedutil uses that same fixed anchor as the reference
plugged into map_util_freq() which saturates exactly at capacity_freq_ref.

As a result, a system with cpufreq boost enabled effectively never runs at
boost frequencies under schedutil-governed load. Fix this by plugging in
policy-max into the map_util_freq equation, so that the DVFS requests
translates to the actual cpufreq driver ceiling.

Signed-off-by: Sibi Sankar <sibi.sankar@oss.qualcomm.com>
---
 kernel/sched/cpufreq_schedutil.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index a1782755efcc..dcefbeaa0702 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -195,10 +195,17 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
 				  unsigned long util, unsigned long max)
 {
 	struct cpufreq_policy *policy = sg_policy->policy;
-	unsigned int freq;
+	unsigned int freq, ref;
 
-	freq = get_capacity_ref_freq(policy);
-	freq = map_util_freq(util, freq, max);
+	ref = get_capacity_ref_freq(policy);
+
+	/*
+	 * That fixed anchor governs how utilization is interpreted, but
+	 * the DVFS request is free to target the current policy ceiling.
+	 * Using ref alone would saturate the util->freq map at ref so
+	 * use policy->max to reach boost frequencies.
+	 */
+	freq = map_util_freq(util, max(ref, READ_ONCE(policy->max)), max);
 
 	if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
 		return sg_policy->next_freq;
-- 
2.34.1