linux-kernel - Re: [PATCH 4/4] arm64: dts: qcom: rename AOSS QMP node to pmu

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Message-ID: <e0e6960d-0aac-ddd7-0a6c-2695f3bf3e61@linaro.org>
Date:   Tue, 13 Dec 2022 08:54:49 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Stephen Boyd <swboyd@...omium.org>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] arm64: dts: qcom: rename AOSS QMP node to pmu

On 12/12/2022 20:08, Stephen Boyd wrote:
> Quoting Krzysztof Kozlowski (2022-12-12 05:33:02)
>> The Always On Subsystem (AOSS) QMP is not a power domain controller
>> since commit 135780456218 ("arm64: dts: qcom: sc7180: Use QMP property
>> to control load state") and few others.  In fact, it was never a power
>> domain controller but rather control of power state of remote
>> processors.  This power state control is know handled differently, thus
>> the AOSS QMP nodes do not have power-domain-cells:
>>
>>   sc7280-idp.dtb: power-controller@...0000: '#power-domain-cells' is a required property
>>   From schema: Documentation/devicetree/bindings/power/power-domain.yaml
>>
>> AOSS QMP is an interface to the actuall AOSS subsystem responsible for
>> some of power management functions, thus let's call the nodes as "pmu" -
>> Power Management Unit.
> 
> Isn't 'pmu' a performance monitoring unit?

No. PMU is whatever you call it... ARM calls it Performance Monitoring
Unit, Samsung and Rockchip (and maybe others) call it Power Management
Unit. It's just an acronym.

Best regards,
Krzysztof