[PATCH v6 0/3] arm64: topology: Handle AMU FIE setup on CPU hotplug

[Lifeng Zheng]

Solve a problem that causes CPUs Setup AMU FIE failed in a corner case,
even though they're eligible.

Changelog:

v6:

 - discard the modifications in cpufreq.c, and instead, make
   supports_scale_freq_counters() checks that at least one CPU in the
   policy supports AMU FIE, instead of all
 - based on Beata's feedback, optimize cpuhp_topology_online() to make it
   more readable
 - use pr_warn instead of WARN_ON to show warning message when the
   freq_counters_valid() check fails in cpuhp_topology_online()
 - modify commit message as Beata and Rafael suggested

v5:

 - add a default implementation for cpufreq_cpu_policy() when
   CONFIG_CPU_FREQ is not defined

v4:

 - change the function's name in patch 2 from
   'cpufreq_cpu_get_raw_no_check' to 'cpufreq_cpu_policy'
 - use only one line in the function body of cpufreq_cpu_policy()
 - use cpus mask instead of related_cpus when calling arch_set_freq_scale()
   in cpufreq.c
 - add a warning when the freq_counters_valid() check fails in
   cpuhp_topology_online()

v3:

 - add a patch to optimize amu_fie_setup()
 - add a patch to add a function to get cpufreq policy without checking if
   the CPU is online
 - discard the reuse of amu_fie_setup() in cpuhp_topology_online() and keep
   all the new logic in cpuhp_topology_online()
 - test only the CPU which is going online in cpuhp_topology_online()
 - when the freq_counters_valid() check fails, not only clear the scale
   freq source but also clear all the related CPUs from amu_fie_cpus mask
 - add some comments

v2:

 - keep init_amu_fie_notifier for setting up AMU FIE when the cpufreq
   policy is being created
 - set up AMU FIE only for online CPUs instead of related_cpus in
   init_amu_fie_callback()
 - check and set all the online CPUs in the same policy when hotplug one
 - clear scale freq source for all the online CPUs in the same policy to
   avoid using different source of the freq scale

---
Discussions of previous version:
v1: https://lore.kernel.org/all/20250607094533.416368-1-zhenglifeng1@huawei.com/
v2: https://lore.kernel.org/all/20250725102813.1404322-1-zhenglifeng1@huawei.com/
v3: https://lore.kernel.org/all/20250805093330.3715444-1-zhenglifeng1@huawei.com/
v4: https://lore.kernel.org/all/20250814072853.3426386-1-zhenglifeng1@huawei.com/
v5: https://lore.kernel.org/all/20250819072931.1647431-1-zhenglifeng1@huawei.com/

Lifeng Zheng (3):
  arm64: topology: Skip already covered CPUs when setting freq source
  cpufreq: Add new helper function returning cpufreq policy
  arm64: topology: Handle AMU FIE setup on CPU hotplug

 arch/arm64/kernel/topology.c | 67 ++++++++++++++++++++++++++++++++++--
 drivers/base/arch_topology.c |  9 ++++-
 drivers/cpufreq/cpufreq.c    |  6 ++++
 include/linux/cpufreq.h      |  5 +++
 4 files changed, 83 insertions(+), 4 deletions(-)

-- 
2.33.0