linux-kernel - Re: [PATCH 2/3] dt-bindings: clock: qcom,gcc-sc7180: document CX power domain

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Message-ID: <6406469d-289b-af4e-83f8-8259f5dcaf00@linaro.org>
Date:   Tue, 11 Apr 2023 15:45:11 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Rajendra Nayak <quic_rjendra@...cinc.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Taniya Das <tdas@...eaurora.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: clock: qcom,gcc-sc7180: document CX
 power domain



On 11.04.2023 15:31, Rajendra Nayak wrote:
> 
> On 4/11/2023 4:57 PM, Konrad Dybcio wrote:
>>
>>
>> On 11.04.2023 06:56, Rajendra Nayak wrote:
>>>
>>>
>>> On 4/8/2023 7:33 PM, Konrad Dybcio wrote:
>>>>
>>>>
>>>> On 8.04.2023 15:48, Krzysztof Kozlowski wrote:
>>>>> The GCC clock controller needs CX power domain, at least according to
>>>>> DTS:
>>>>>
>>>>>     sc7180-trogdor-pompom-r3.dtb: clock-controller@...000: Unevaluated properties are not allowed ('power-domains' was unexpected)
>>>>>
>>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>>>>> ---
>>>> +CC Rajendra (author of 5d6fc6321db1 ("arm64: dts: qcom:
>>>> sc7180: Add required-opps for USB"))
>>>>
>>>> Rajendra, shouldn't SC7180 GCC have PM ops to make sure a vote
>>>> is only there when AP is active?
>> So IIUC, CX is never supposed to be shut down?
> 
> Atleast sc7180 and sc7280 do not support full CX shutdown (or power
> collapse as its called), it only transitions to a Retention state
> and even that in the system-wide suspend path only
And won't outstanding votes on that resource prevent the system
from entering a system-wide low power state?

Konrad
> 
>>
>> Konrad
>>>
>>> hmm, I am not quite sure why we would want the performance votes
>>> from peripherals dropped when CPUs go down in idle?
>>>
>>>> Are all GDSCs powered by CX?
>>>> If not, wouldn't this also need power-domain-names to
>>>> facilitate e.g. potential MX-powered ones?
>>>
>>> For sc7180 GCC, yes.
>>>
>>>>
>>>> Konrad
>>>>>    .../devicetree/bindings/clock/qcom,gcc-sc7180.yaml         | 7 +++++++
>>>>>    1 file changed, 7 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/clock/qcom,gcc-sc7180.yaml b/Documentation/devicetree/bindings/clock/qcom,gcc-sc7180.yaml
>>>>> index 06dce0c6b7d0..8bf9b6f49550 100644
>>>>> --- a/Documentation/devicetree/bindings/clock/qcom,gcc-sc7180.yaml
>>>>> +++ b/Documentation/devicetree/bindings/clock/qcom,gcc-sc7180.yaml
>>>>> @@ -32,6 +32,10 @@ properties:
>>>>>          - const: bi_tcxo_ao
>>>>>          - const: sleep_clk
>>>>>    +  power-domains:
>>>>> +    items:
>>>>> +      - description: CX domain
>>>>> +
>>>>>    required:
>>>>>      - compatible
>>>>>      - clocks
>>>>> @@ -45,6 +49,8 @@ unevaluatedProperties: false
>>>>>    examples:
>>>>>      - |
>>>>>        #include <dt-bindings/clock/qcom,rpmh.h>
>>>>> +    #include <dt-bindings/power/qcom-rpmpd.h>
>>>>> +
>>>>>        clock-controller@...000 {
>>>>>          compatible = "qcom,gcc-sc7180";
>>>>>          reg = <0x00100000 0x1f0000>;
>>>>> @@ -52,6 +58,7 @@ examples:
>>>>>                   <&rpmhcc RPMH_CXO_CLK_A>,
>>>>>                   <&sleep_clk>;
>>>>>          clock-names = "bi_tcxo", "bi_tcxo_ao", "sleep_clk";
>>>>> +      power-domains = <&rpmhpd SC7180_CX>;
>>>>>          #clock-cells = <1>;
>>>>>          #reset-cells = <1>;
>>>>>          #power-domain-cells = <1>;