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

[zhenglifeng (A)]

On 2025/12/13 4:08, Will Deacon wrote:
> On Fri, Dec 12, 2025 at 05:27:09PM +0800, zhenglifeng (A) wrote:
>> On 2025/12/2 23:31, Beata Michalska wrote:
>>> On Tue, Dec 02, 2025 at 11:05:25AM +0800, zhenglifeng (A) wrote:
>>>> On 2025/12/1 23:27, Beata Michalska wrote:
>>>>> Hi,
>>>>>
>>>>> Apologies for the delay in reviewing this - currently in progress....
>>>>> Out of curiosity: what's the cpufreq driver used for testing this series ?
>>>>
>>>> I used cppc_cpufreq for testing this. But with some modifications in
>>>> processor_driver.c, or you'll find that the driver will fail to load with
>>>> maxcpus set. The modification below is only a temporary solution. I'm still
>>>> working on that.
>>>>
>>> Right, so overall the implementation looks good - thanks for that.
>>> There are two issues though with the cppc cpufreq driver.
>>>
>>> One: as you have already noticed - it fails to register when
>>> cpumask_present != cpumask_online.
>>>
>>> Second: it will mix the sources of the freq scale if not all CPUs within the
>>> policy have AMUs enabled/valid. This is due to the fact that at the time of
>>> registering the driver and initializing the FIE support policy->cpus ==
>>> policy->related_cpus. Assuming scenario when there are two CPUs within the
>>> policy, one being offline and missing valid AMU counters,
>>> the topology_set_scale_freq_source from cppc cpufreq driver will register
>>> the tick handler for both CPUs, whereas AMU support will (rightly so) register
>>> only for the firs one. When the second CPU comes online, the mismatch will be
>>> detected and the arch callback will get cleared for the first CPU, but the
>>> second one will remain unchanged.
>>>
>>> That said, I do not think any of those issues is a blocker for this series.
>>> But both would need fixing.
>>
>> I believe Beata is OK with this series. So I think we can move ahead with it
>> now.
> 
> Please repost at -rc1. It would be nice to have an Ack from Beata...

Hi Beata,

It would be nice if you could give this patch an Ack.

Thanks.

> 
> Will
>