linux-kernel - Re: [PATCH v2 0/4] thermal: core/ACPI: Fix processor cooling device regression

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Date:   Mon, 13 Mar 2023 19:02:10 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     "Zhang, Rui" <rui.zhang@...el.com>
Cc:     "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "srinivas.pandruvada@...ux.intel.com" 
        <srinivas.pandruvada@...ux.intel.com>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        "Wang, Quanxian" <quanxian.wang@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH v2 0/4] thermal: core/ACPI: Fix processor cooling device regression

On Mon, Mar 13, 2023 at 5:47 PM Zhang, Rui <rui.zhang@...el.com> wrote:
>
> Hi, Rafael,
>
> The only concern to me is that, in thermal_cooling_device_update(), we
> should handle the cases that the cooling device is current used by
> one/more thermal zone. say, something like
>
> list_for_each_entry(pos, &cdev->thermal_instances, cdev_node) {
>         /* e.g. what to do if tz1 set it to state 1 previously */
> }
> I have not got a clear idea what we should do here.

For each instance, set upper to max_state if above it and set target
to upper if above it I'd say.

I guess otherwise there may be some confusion in principle and I have
missed that piece, so thanks for pointing it out!

> But given that I have confirmed that this patch series fixes the
> original problem, and the ACPI passive cooling is unlikely to be
> triggered before CPUFREQ_CREATE_POLICY notification, probably we can
> address that problem later.
>
> Tested-by: Zhang Rui <rui.zhang@...el.com>
> Reviewed-by: Zhang Rui <rui.zhang@...el.com>

Thank you!