linux-kernel - Re: [PATCH v1 1/2] dt-binding: usb: ci-hdrc-usb2: document Nuvoton NPCM supprt

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Message-ID: <20230919162837.GA4051010-robh@kernel.org>
Date:   Tue, 19 Sep 2023 11:28:37 -0500
From:   Rob Herring <robh@...nel.org>
To:     Tomer Maimon <tmaimon77@...il.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        peter.chen@...nel.org, gregkh@...uxfoundation.org,
        krzysztof.kozlowski+dt@...aro.org, xu.yang_2@....com,
        peng.fan@....com, avifishman70@...il.com, tali.perry1@...il.com,
        joel@....id.au, venture@...gle.com, yuenn@...gle.com,
        benjaminfair@...gle.com, j.neuschaefer@....net,
        openbmc@...ts.ozlabs.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v1 1/2] dt-binding: usb: ci-hdrc-usb2: document Nuvoton
 NPCM supprt

On Tue, Sep 19, 2023 at 04:31:56PM +0300, Tomer Maimon wrote:
> On Tue, 19 Sept 2023 at 15:39, Krzysztof Kozlowski
> <krzysztof.kozlowski@...aro.org> wrote:
> >
> > On 19/09/2023 07:14, Tomer Maimon wrote:
> > >>>            - nvidia,tegra20-ehci
> > >>>            - nvidia,tegra20-udc
> > >>>            - nvidia,tegra30-ehci
> > >>> @@ -325,6 +326,20 @@ properties:
> > >>>      type: boolean
> > >>>      deprecated: true
> > >>>
> > >>> +  nuvoton,sysgcr:
> > >>> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> > >>> +    items:
> > >>> +      - items:
> > >>> +          - description: phandle to syscon that configures usb phy mux.
> > >>> +          - description: offset of usb phy mux selection.
> > >>> +          - description: mask usb phy mux selection.
> > >>> +          - description: value usb phy mux selection.
> > >>> +    description:
> > >>> +      A phandle to syscon with three arguments that configure usb phy mux.
> > >>> +      The argument one is the offset of usb phy mux selection, the argument two
> > >>> +      is the mask usb phy mux selection, the argument three is the mask usb phy
> > >>> +      mux selection.
> > >>
> > >> Sorry, you miss phy driver. Don't use syscon instead of proper hardware
> > >> devices.
> > > Sorry the role of nuvoton,sysgcr property is to handle a mux between
> > > the different devices and not the handle the phy itself, handle the
> > > mux done in the GCR.
> > > Should we move the nuvoton,sysgcr description to another place in the
> > > ci-hdrc-usb2.yaml
> > > or
> > > Should we use a different driver to handle the mux and call it from
> > > the ci-hdrc-npcm driver, If yes which driver should we use?
> >
> > What is an "usb phy mux"?
> We have USB phy that could be connected to USB host (different driver)
> or it can be connected to the UDC driver(ChipIdea)

Isn't that just role switching? There is a driver framework for that in 
drivers/usb/roles/. Though it doesn't seem widely used yet.

Rob