linux-kernel - Re: [PATCH] cpufreq: Add CPU frequency policy change notification support

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Message-ID: <345044bb-15e8-48d3-bc03-d5f327aeb3ae@zhaoxin.com>
Date: Wed, 21 Jan 2026 16:37:48 +0800
From: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
CC: <rafael@...nel.org>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <CobeChen@...oxin.com>, <TimGuo@...oxin.com>,
	<LeoLiu-oc@...oxin.com>, <LindaChai@...oxin.com>
Subject: Re: [PATCH] cpufreq: Add CPU frequency policy change notification
 support



On 2026/1/21 13:51, Viresh Kumar wrote:
> 
> 
> 
> On 20-01-26, 17:24, Tony W Wang-oc wrote:
>> Implemented CPUFREQ_CHANGE_POLICY notification in cpufreq subsystem.
>> This enhancement allows kernel modules to be notified when a CPU frequency
>> policy is modified, facilitating more integrated system management.
>> The notification is dispatched after a successful governor switch during
>> policy updates.
>>
>> Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
>> ---
>>   drivers/cpufreq/cpufreq.c | 2 ++
>>   include/linux/cpufreq.h   | 1 +
>>   2 files changed, 3 insertions(+)
> 
> Who is using this stuff ? Please explain why you need this and how you
> are going to use it. I don't think it is a great idea, but I still
> want to see what you are doing in the first place.
> 

The expectation is to register a notifier of type 
CPUFREQ_POLICY_NOTIFIER via cpufreq_register_notifier in one of our 
drivers. The notifier callback will configure Zhaoxin registers to 
different values based on the different cpufreq governors when the event 
is CPUFREQ_GOVERNOR_CHANGE, thereby allowing the Zhaoxin hardware to 
adopt different power management strategies.

Sincerely!
TonyWWang-oc