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

[Beata Michalska <beata.michalska@arm.com>]

Hi,

Apologies for the delay in reviewing this - currently in progress....
Out of curiosity: what's the cpufreq driver used for testing this series ?

---
BR
Beata
On Wed, Nov 19, 2025 at 04:13:53PM +0800, Lifeng Zheng wrote:
> 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
>