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From:   Doug Anderson <dianders@chromium.org>
Date:   Tue, 27 Mar 2018 14:37:53 -0700
Message-ID: <CAD=FV=Vwx2nW=pwEzJJSVXLctxOU5uGormBn=t_P6_xyfrrLAw@mail.gmail.com>
Subject: Re: [PATCH v3 3/6] dt-bindings: phy-qcom-qmp: Update bindings for sdm845
To:     Manu Gautam <mgautam@codeaurora.org>,
        Rob Herring <robh+dt@kernel.org>
Cc:     Kishon Vijay Abraham I <kishon@ti.com>,
        LKML <linux-kernel@vger.kernel.org>, devicetree@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
        Vivek Gautam <vivek.gautam@codeaurora.org>,
        Varadarajan Narayanan <varada@codeaurora.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi,

On Thu, Mar 22, 2018 at 11:11 PM, Manu Gautam <mgautam@codeaurora.org> wrote:
> Update compatible strings for USB3 PHYs on SDM845.
> One is QMPv3 DisplayPort-USB combo PHY and other one
> is USB UNI PHY which is single lane USB3 PHY without
> DP capability.
>
> Reviewed-by: Rob Herring <robh@kernel.org>
> Signed-off-by: Manu Gautam <mgautam@codeaurora.org>
> ---
>  Documentation/devicetree/bindings/phy/qcom-qmp-phy.txt | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/phy/qcom-qmp-phy.txt b/Documentation/devicetree/bindings/phy/qcom-qmp-phy.txt
> index dcf1b8f..cef8765 100644
> --- a/Documentation/devicetree/bindings/phy/qcom-qmp-phy.txt
> +++ b/Documentation/devicetree/bindings/phy/qcom-qmp-phy.txt
> @@ -9,7 +9,9 @@ Required properties:
>                "qcom,ipq8074-qmp-pcie-phy" for PCIe phy on IPQ8074
>                "qcom,msm8996-qmp-pcie-phy" for 14nm PCIe phy on msm8996,
>                "qcom,msm8996-qmp-usb3-phy" for 14nm USB3 phy on msm8996,
> -              "qcom,qmp-v3-usb3-phy" for USB3 QMP V3 phy.
> +              "qcom,qmp-v3-usb3-phy" for USB3 QMP V3 phy,
> +              "qcom,sdm845-qmp-usb3-phy" for USB3 QMP V3 phy on sdm845,
> +              "qcom,sdm845-qmp-usb3-uni-phy" for USB3 QMP V3 UNI phy on sdm845.

I'm confused.  What value does "qcom,qmp-v3-usb3-phy" have as a
separate entry from "qcom,sdm845-qmp-usb3-phy"?  Is
"qcom,qmp-v3-usb3-phy" expected to work on some non-SDM845 based
device?

Personally I think you should remove "qcom,qmp-v3-usb3-phy" from the
bindings as part of this patch (replacing it with the new string
qcom,sdm845-qmp-usb3-phy)".  Yeah, yeah bindings are forever.  ...but
that particular string was added about a month ago and (I believe) it
was intended for SDM845 anyway.  As per
<https://patchwork.kernel.org/patch/10302759/> match to the exact same
PHY data which leads extra credence to my belief.

If later on you find that some future chip can use the exact same
driver / settings as the SDM845 you can always list the
"qcom,sdm845-qmp-usb3-phy" string as a secondary compatible anyway.


-Doug