Re: [PATCH v7 1/2] cpufreq: Remove per-CPU QoS constraint

[Pierre Gondois <pierre.gondois@arm.com>]

On 3/26/26 05:37, Viresh Kumar wrote:
> What do you mean by per-CPU QOS constraint in Subject ? This is per-policy
> constraint and you are not removing it, you are just avoiding to update it in
> one of the paths.
Right, I ll update the patch header
> On 25-03-26, 17:52, Pierre Gondois wrote:
>> policy->max_freq_req QoS constraint represents the maximal allowed
>> frequency than can be requested. It is set by:
>> - writing to policyX/scaling_max sysfs file
>> - toggling the cpufreq/boost sysfs file
>>
>> Upon calling freq_qos_update_request(), a successful update
>> of the max_freq_req value triggers cpufreq_notifier_max(),
>> followed by cpufreq_set_policy() which update the requested
>> frequency for the policy.
>> If the new max_freq_req value is not different from the
>> original value, no frequency update is triggered.
>>
>> In a specific sequence of toggling:
>> - cpufreq/boost sysfs file
>> - CPU hot-plugging
>> a CPU could end up with boost enabled but running at the
>> maximal non-boost frequency, cpufreq_notifier_max() not being
>> triggered. The following fixed that:
>> commit 1608f0230510 ("cpufreq: Fix re-boost issue after hotplugging
>> a CPU")
>>
>> The following:
>> commit dd016f379ebc ("cpufreq: Introduce a more generic way to
>> set default per-policy boost flag")
>> also fixed the issue by correctly setting the max_freq_req
>> constraint of a policy that is re-activated. This makes the
>> first fix unnecessary.
>>
>> As the original issue is fixed by another method,
>> this patch reverts:
>> commit 1608f0230510 ("cpufreq: Fix re-boost issue after hotplugging
>> a CPU")
> Looks okay otherwise.
>