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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Thu, 4 Jan 2024 12:30:57 +0200
Message-ID: <CAA8EJprAy4cjLw9jBPQ4Oh+g8d5aGmFx1pWaYv_kzF7xTsvGKA@mail.gmail.com>
Subject: Re: [PATCH] arm64: dts: qcom: ipq6018: add #power-domain-cells for
 gcc node
To: Fenglin Wu <quic_fenglinw@quicinc.com>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>, quic_tdas@quicinc.com, 
	quic_aiquny@quicinc.com, kernel@quicinc.com, Andy Gross <agross@kernel.org>, 
	Bjorn Andersson <andersson@kernel.org>, Rob Herring <robh+dt@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, 
	linux-kernel@vger.kernel.org
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On Thu, 4 Jan 2024 at 12:27, Fenglin Wu <quic_fenglinw@quicinc.com> wrote:
>
>
>
> On 1/4/2024 6:16 PM, Konrad Dybcio wrote:
> > On 4.01.2024 11:13, Fenglin Wu wrote:
> >>
> >>
> >> On 1/4/2024 5:53 PM, Dmitry Baryshkov wrote:
> >>> On Thu, 4 Jan 2024 at 10:06, Fenglin Wu via B4 Relay
> >>> <devnull+quic_fenglinw.quicinc.com@kernel.org> wrote:
> >>>>
> >>>> From: Fenglin Wu <quic_fenglinw@quicinc.com>
> >>>>
> >>>> Property '#power-domain-cells' is required as per defined in qcom,gc=
c.yaml
> >>>> so add it for ipq6018 gcc device node to eliminate following warning=
 in
> >>>> dtbs_check:
> >>>>
> >>>> arch/arm64/boot/dts/qcom/ipq6018-cp01-c1.dtb: gcc@1800000:
> >>>>           '#power-domain-cells' is a required property
> >>>> from schema $id: http://devicetree.org/schemas/clock/qcom,gcc-ipq601=
8.yaml#
> >>>
> >>> But ipq6018 doesn't implement GDSC support. So for the sake of fixing
> >>> the warning you are adding a bogus property.
> >>>
> >> I agree. However, there are also some gcc drivers not implementing GDS=
C support but the bindings are adding '#power-domain-cells' in the DT examp=
le, such as: qcom,gcc-apq8064.yaml, qcom,gcc-ipq4019.yaml, qcom,gcc-ipq6018=
.yaml, qcom,gcc-ipq8064.yaml, qcom,gcc-msm8660.yaml.
> >>
> >> Actually I thought that maybe we should do a clean up by removing '#po=
wer-domain-cells' out of the qcom,gcc.yaml binding and only adding it into =
individual qcom,gcc-xxx.yaml for the driver which has implemented GDSC supp=
ort. I checked this with Taniya offline, but she prefers only fixing it in =
ipq6018.dtsi as it doesn't hurt anything by adding the property, and she ex=
pects the GDSC support should be existing in most of qcom,gcc drivers espec=
ially the newer Qcom chipsets.
> >
> > Before we start changing anything, we should assess whether these
> > platforms actually have GDSCs within this clock controller block,
> > even if they are (currently) not described in the clk driver.
> >
> I would assume '#power-domain-cells' is only required for drivers which
> register GDSC as power-domain device, for drivers that only configure
> GDSC during probe or for platforms have GDSC but not register them as
> power-domain device, making '#power-domain-cells' as a required property
> doesn't help anything but just generating more dtbs check warnings.

If there is a hardware GDSC, it should be registered in software
unless there is a good reason to do otherwise.


--=20
With best wishes
Dmitry