commit 500ba33284 upstream.
pm_domain_cpu_gov is selecting a cluster idle state but does not consider
latency tolerance of child CPUs. This results in deeper cluster idle state
whose latency does not meet latency tolerance requirement.
Select deeper idle state only if global and device latency tolerance of all
child CPUs meet.
Test results on SM8750 with 300 usec PM-QoS on CPU0 which is less than
domain idle state entry (2150) + exit (1983) usec latency mentioned in
devicetree, demonstrate the issue.
# echo 300 > /sys/devices/system/cpu/cpu0/power/pm_qos_resume_latency_us
Before: (Usage is incrementing)
======
# cat /sys/kernel/debug/pm_genpd/power-domain-cluster0/idle_states
State Time Spent(ms) Usage Rejected Above Below
S0 29817 537 8 270 0
# cat /sys/kernel/debug/pm_genpd/power-domain-cluster0/idle_states
State Time Spent(ms) Usage Rejected Above Below
S0 30348 542 8 271 0
After: (Usage is not incrementing due to latency tolerance)
======
# cat /sys/kernel/debug/pm_genpd/power-domain-cluster0/idle_states
State Time Spent(ms) Usage Rejected Above Below
S0 39319 626 14 307 0
# cat /sys/kernel/debug/pm_genpd/power-domain-cluster0/idle_states
State Time Spent(ms) Usage Rejected Above Below
S0 39319 626 14 307 0
Signed-off-by: Maulik Shah <maulik.shah@oss.qualcomm.com>
Fixes: e94999688e ("PM / Domains: Add genpd governor for CPUs")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250709-pmdomain_qos-v2-1-976b12257899@oss.qualcomm.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
11c19d42d3