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Date:   Thu, 24 Jun 2021 10:48:12 +0100
From:   Ionela Voinescu <ionela.voinescu@arm.com>
To:     Viresh Kumar <viresh.kumar@linaro.org>
Cc:     Rafael Wysocki <rjw@rjwysocki.net>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        linux-pm@vger.kernel.org, Qian Cai <quic_qiancai@quicinc.com>,
        linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 4/4] cpufreq: CPPC: Add support for frequency
 invariance
Message-ID: <20210624094812.GA6095@arm.com>
References: <cover.1624266901.git.viresh.kumar@linaro.org>
 <f963d09e57115969dae32827ade5558b0467d3a0.1624266901.git.viresh.kumar@linaro.org>
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In-Reply-To: <f963d09e57115969dae32827ade5558b0467d3a0.1624266901.git.viresh.kumar@linaro.org>
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Hey,

On Monday 21 Jun 2021 at 14:49:37 (+0530), Viresh Kumar wrote:
> The Frequency Invariance Engine (FIE) is providing a frequency scaling
> correction factor that helps achieve more accurate load-tracking.
[..]
> +static void cppc_cpufreq_cpu_fie_exit(struct cpufreq_policy *policy)
> +{
> +	struct cppc_freq_invariance *cppc_fi;
> +	int cpu;
> +
> +	if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
> +		return;
> +
> +	/* policy->cpus will be empty here, use related_cpus instead */
> +	topology_clear_scale_freq_source(SCALE_FREQ_SOURCE_CPPC, policy->related_cpus);
> +
> +	for_each_cpu(cpu, policy->related_cpus) {
> +		cppc_fi = &per_cpu(cppc_freq_inv, cpu);

Do you think it might be worth having here something like:

		if (!cppc_fi->cpu_data)
			continue;

This would be to protect against cases where the platform does not boot
with all CPUs or the module is loaded after some have already been
offlined. Unlikely, but..

> +		irq_work_sync(&cppc_fi->irq_work);
> +		kthread_cancel_work_sync(&cppc_fi->work);
> +	}
> +}

The rest of the code is almost the same as the original, so that is all
from me :).

Thanks,
Ionela.