linux-kernel - Re: [PATCH v5 1/3] dt-bindings: phy: qcom,qmp: Convert QMP PHY bindings to yaml

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Message-ID: <20200423171436.GJ199755@google.com>
Date:   Thu, 23 Apr 2020 10:14:36 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Doug Anderson <dianders@...omium.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Sandeep Maheswaram <sanm@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Manu Gautam <mgautam@...eaurora.org>,
        Tanmay Shah <tanmay@...eaurora.org>, robdclark@...il.com,
        abhinavk@...eaurora.org, nganji@...eaurora.org,
        jsanka@...eaurora.org, aravindh@...eaurora.org,
        hoegsberg@...gle.com, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v5 1/3] dt-bindings: phy: qcom,qmp: Convert QMP PHY
 bindings to yaml

Hi Sandeep,

On Tue, Apr 14, 2020 at 02:21:17PM -0700, Stephen Boyd wrote:
> Quoting Sandeep Maheswaram (2020-04-01 23:38:52)
> > Convert QMP PHY bindings to DT schema format using json-schema.
> > 
> > Signed-off-by: Sandeep Maheswaram <sanm@...eaurora.org>
> > ---
> >  .../devicetree/bindings/phy/qcom,qmp-phy.yaml      | 332 +++++++++++++++++++++
> >  .../devicetree/bindings/phy/qcom-qmp-phy.txt       | 242 ---------------
> >  2 files changed, 332 insertions(+), 242 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/phy/qcom,qmp-phy.yaml
> >  delete mode 100644 Documentation/devicetree/bindings/phy/qcom-qmp-phy.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/phy/qcom,qmp-phy.yaml b/Documentation/devicetree/bindings/phy/qcom,qmp-phy.yaml
> > new file mode 100644
> > index 0000000..18a8985
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/qcom,qmp-phy.yaml
> > @@ -0,0 +1,332 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +
> > +%YAML 1.2
> > +---
> > +$id: "http://devicetree.org/schemas/phy/qcom,qmp-phy.yaml#"
> > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> > +
> > +title: Qualcomm QMP PHY controller
> > +
> > +maintainers:
> > +  - Manu Gautam <mgautam@...eaurora.org>
> > +
> > +description:
> > +  QMP phy controller supports physical layer functionality for a number of
> > +  controllers on Qualcomm chipsets, such as, PCIe, UFS, and USB.
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - qcom,ipq8074-qmp-pcie-phy
> > +      - qcom,msm8996-qmp-pcie-phy
> > +      - qcom,msm8996-qmp-ufs-phy
> > +      - qcom,msm8996-qmp-usb3-phy
> > +      - qcom,msm8998-qmp-pcie-phy
> > +      - qcom,msm8998-qmp-ufs-phy
> > +      - qcom,msm8998-qmp-usb3-phy
> > +      - qcom,sdm845-qhp-pcie-phy
> > +      - qcom,sdm845-qmp-pcie-phy
> > +      - qcom,sdm845-qmp-ufs-phy
> > +      - qcom,sdm845-qmp-usb3-phy
> > +      - qcom,sdm845-qmp-usb3-uni-phy
> > +      - qcom,sm8150-qmp-ufs-phy
> > +
> > +  reg:
> > +    minItems: 1
> > +    items:
> > +      - description: Address and length of PHY's common serdes block.
> > +      - description: Address and length of the DP_COM control block.
> 
> This DP_COM block is only for one compatible. Is it possible to split
> that compatible out of this binding so we can enforce the reg property
> being either one or two items?
> 
> In addition, I don't quite understand how this binding is supposed to
> work with the DP phy that sits inside qcom,sdm845-qmp-usb3-phy and then
> gets muxed out on the USB pins on sdm845 and sc7180 SoCs. Can you fill
> me in on how we plan to share the pins between the two phys so that all
> the combinations of DP and USB over the type-c pins will work here? My
> understanding is that the pins that are controlled by this hardware
> block are basically a full USB type-c connector pinout[1] (except that
> D+/D- isn't there and the VBUS and CC lines go to the PMIC). Either way,
> we get the TX1/2 and RX1/2 pins to use, so we can do 4x lanes of DP or
> 2x lanes DP and 2x lanes of USB. There's also a type-c orientation
> flipper bit that can flip the DP and USB phy lanes to the correct TX/RX
> pins on the SoC. And then the DP phy has a lane remapper to change the
> logical DP lane to the physical DP lane. It's a complex piece of
> hardware that isn't fully represented by this binding.
> 
> [1] https://en.wikipedia.org/wiki/USB-C#/media/File:USB_Type-C_Receptacle_Pinout.svg

Could you please answer Stephen's questions? It would be great to move
forward and get support for SC7180 landed.