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    SubjectRe: [RFC PATCH v2 3/3] dt-bindings: usb: snps,dwc3: add generic-xhci as child
    On Mon, Jan 02, 2023 at 02:45:17PM +0900, Jung Daehwan wrote:
    > On Thu, Dec 29, 2022 at 11:23:02AM +0100, Krzysztof Kozlowski wrote:
    > > On 29/12/2022 10:57, Daehwan Jung wrote:
    > > > Currently, dwc3 invokes just xhci platform driver(generic-xhci) without
    > > > DT schema even though xhci works as child of dwc3. It makes sense to add
    > > > xhci as child of dwc3 with DT schema. It also supports to use another
    > > > compatible in xhci platform driver.
    > >
    > > You use some driver as an argument for hardware description, which is
    > > not what we need. Describe the hardware.
    > >
    >
    > OK. I will it on next submission.
    >
    > > >
    > > > Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
    > > > ---
    > > > .../devicetree/bindings/usb/snps,dwc3.yaml | 29 +++++++++++++++++++
    > > > 1 file changed, 29 insertions(+)
    > > >
    > > > diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
    > > > index 6d78048c4613..83ed7c526dba 100644
    > > > --- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
    > > > +++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
    > > > @@ -360,8 +360,22 @@ properties:
    > > > description:
    > > > Enable USB remote wakeup.
    > > >
    > > > + "#address-cells":
    > > > + enum: [ 1, 2 ]
    > > > +
    > > > + "#size-cells":
    > > > + enum: [ 1, 2 ]
    > > > +
    > > > + ranges: true
    > > > +
    > > > unevaluatedProperties: false
    > > >
    > > > +# Required child node:
    > > > +patternProperties:
    > > > + "^usb@[0-9a-f]+$":
    > > > + $ref: generic-xhci.yaml#
    > > > + description: Required child node
    > >
    > > DWC does not have another piece of controller as child... DWC is the
    > > controller. Not mentioning that you now affect several other devices
    > > without describing the total hardware picture (just some drivers which
    > > is not that relevant).
    > >
    >
    > DWC controller supports USB Host mode and it uses same resource and
    > really works as a child. I guess it's same on many SOCs, especially
    > mobile..

    Yes, and we already support all those platforms just fine without this
    child node. Adding it means we have to then support *both* ways in the
    driver.


    > I just want to modify it to work with DT schema (dwc3 -> xhci-plat).
    > I think it needs to dicuss more..

    Why doesn't it work with the schema?

    It's convenient when DT nodes == device drivers, but hardware is messy
    sometimes. Linux (and other OSs) have to deal with that. We can't write
    the DT to reflect the current (and evolving) needs of a particular OS.

    Rob

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