linux-kernel - Re: [PATCH v2 3/3] cpufreq: Update set_boost callbacks to rely on boost_freq

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Message-ID: <ppzoeb4wod6jjhlvkiqogcd26v3shfh5cjiuq63r7bbnsyzzok@sdx5usgvcqzu>
Date: Tue, 13 Jan 2026 07:00:40 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Pierre Gondois <pierre.gondois@....com>
Cc: "zhenglifeng (A)" <zhenglifeng1@...wei.com>, 
	linux-kernel@...r.kernel.org, Christian Loehle <christian.loehle@....com>, 
	Ionela Voinescu <ionela.voinescu@....com>, Jie Zhan <zhanjie9@...ilicon.com>, Huang Rui <ray.huang@....com>, 
	"Gautham R. Shenoy" <gautham.shenoy@....com>, Mario Limonciello <mario.limonciello@....com>, 
	Perry Yuan <perry.yuan@....com>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 3/3] cpufreq: Update set_boost callbacks to rely on
 boost_freq_req

On 12-01-26, 16:02, Pierre Gondois wrote:
> In:
> cpufreq_set_policy()
> \-cpufreq_driver->verify(&new_data)
>   \-cpufreq_verify_within_cpu_limits()
> 
> the requested min/max values are clamped wrt the cpuinfo.[min|max]_freq.
> However this clamping happens after the QoS constraints have been
> aggregated. This means that if a CPU has:
> - min = 100.000 kHz
> - max = 1.000.000 kHz
> - boost = 1.200.000 kHz
> 
> With boost enabled, the user requests:
> - scaling_min: 1.100.000
> - scaling_max: 1.200.000
> 
> If boost is disabled, we will have:
> policy->min == policy->max == 1.000.000
> without notifying anybody.
> 
> Ideally I assume it would be better to prevent the user from disabling
> boost without first asking to update the scaling_[min|max] frequencies,
> or at least detecting this case and have a warning message.

I don't think this is a problem and doesn't really need special care.
It is the user who is disabling the boost feature, its okay to force
set to clamped values.

> Please let me know if you prefer not adding the new qos constraint,
> I ll try harder not to have it if yes.

But even with that (the issue pointed earlier not being a problem), I
think a new constraint for boost does make the code cleaner and easy
to follow.

Rafael ?

-- 
viresh