linux-kernel - Re: [PATCH] arm64: dts: qcom: x1e80100: Add '#cooling-cells' for CPU nodes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <a709a83a-326e-4555-9431-1c7654793157@oss.qualcomm.com>
Date: Thu, 18 Dec 2025 14:44:02 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>,
        Manivannan Sadhasivam <mani@...nel.org>, andersson@...nel.org,
        konradybcio@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
        conor+dt@...nel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: x1e80100: Add '#cooling-cells' for CPU
 nodes

On 12/18/25 2:40 PM, Dmitry Baryshkov wrote:
> On Thu, Dec 18, 2025 at 01:54:30PM +0100, Konrad Dybcio wrote:
>> On 12/8/25 6:13 AM, Manivannan Sadhasivam wrote:
>>> On Sun, Oct 19, 2025 at 07:01:30PM +0300, Dmitry Baryshkov wrote:
>>>> On Wed, Oct 15, 2025 at 12:27:03PM +0530, Manivannan Sadhasivam wrote:
>>>>> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
>>>>>
>>>>> Enable passive cooling for CPUs in the X1E80100 SoC by adding the
>>>>> '#cooling-cells' property. This will allow the OS to mitigate the CPU
>>>>> power dissipation with the help of SCMI DVFS.
>>>>
>>>> #cooling-cells isn't enough, the devices need to be listed in the
>>>> thermal maps.
>>>>
>>>
>>> Not strictly required unless the cooling device and trip points are wired in DT.
>>> But I don't want to do that yet, and just expose the cooling devices to
>>> userspace so that I can experiment with something like thermal-daemon.
>>
>> Rob, Krzysztof,
>>
>> Would it be an overly ambitious idea to make #cooling-cells required for
>> CPU nodes? I'd imagine some sort of cpuidle or cpufreq is desired on almost
>> all platforms, which could be used as a cooling/throttling measure..
> 
> Looking at my museum, i.MX devices don't have #cooling-cells before
> i.MX6.

Right, but they are still arm platforms so they have the wfi instruction,
meaning *some* sort of idle injection could happen as a cooling measure

I was wondering if there's any ancient platforms (probably from the 90s?)
that wouldn't even feature such things (and hence it wouldn't make sense
to define CPUs as cooling devices).. such old platforms would probably be
single-core, so turning off auxiliary ones as a last resort wouldn't work
either

Konrad