Re: [PATCH v3 1/4] dt-bindings: usb: dwc3: Add Google Tensor G5 DWC3

[Roy Luo <royluo@google.com>]

On Fri, Oct 10, 2025 at 5:09 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 10/10/2025 22:16, Roy Luo wrote:
> > Document the device tree bindings for the DWC3 USB controller found in
> > Google Tensor SoCs, starting with the G5 generation.
> >
> > The Tensor G5 silicon represents a complete architectural departure from
> > previous generations (like gs101), including entirely new clock/reset
> > schemes, top-level wrapper and register interface. Consequently,
> > existing Samsung/Exynos DWC3 USB bindings are incompatible, necessitating
> > this new device tree binding.
> >
> > The USB controller on Tensor G5 is based on Synopsys DWC3 IP and features
> > Dual-Role Device single port with hibernation support.
>
> You still mix, completely unnecessarily, subsystems. For Greg this is
> actually even undesired, but regardless don't do this for any cases
> because it just makes everything slower or more difficult to apply.
>
> Really, think how maintainers should deal with your patches.
>

Understood, I will separate the patches into two distinct series: one for
the controller and one for the PHY.
Appreciate the feedback and the explanation.

> >
> > Signed-off-by: Roy Luo <royluo@google.com>
> > ---
> >  .../bindings/usb/google,gs5-dwc3.yaml         | 141 ++++++++++++++++++
> >  1 file changed, 141 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/usb/google,gs5-dwc3.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/usb/google,gs5-dwc3.yaml b/Documentation/devicetree/bindings/usb/google,gs5-dwc3.yaml
> > new file mode 100644
> > index 000000000000..6fadea7f41e8
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/google,gs5-dwc3.yaml
> > @@ -0,0 +1,141 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +# Copyright (c) 2025, Google LLC
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/usb/google,gs5-dwc3.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Google Tensor Series (G5+) DWC3 USB SoC Controller
> > +
> > +maintainers:
> > +  - Roy Luo <royluo@google.com>
> > +
> > +description:
> > +  Describes the DWC3 USB controller block implemented on Google Tensor SoCs,
> > +  starting with the G5 generation. Based on Synopsys DWC3 IP, the controller
> > +  features Dual-Role Device single port with hibernation add-on.
> > +
> > +properties:
> > +  compatible:
> > +    const: google,gs5-dwc3
> > +
> > +  reg:
> > +    items:
> > +      - description: Core DWC3 IP registers.
> > +      - description: USB host controller configuration registers.
> > +      - description: USB custom interrrupts control registers.
> > +
> > +  reg-names:
> > +    items:
> > +      - const: dwc3_core
> > +      - const: host_cfg
> > +      - const: usbint_cfg
> > +
> > +  interrupts:
> > +    items:
> > +      - description: Core DWC3 interrupt.
> > +      - description: High speed power management event for remote wakeup from hibernation.
> > +      - description: Super speed power management event for remote wakeup from hibernation.
>
> Wrap at 80 (see coding style) or just shorten these.

Ack, will fix it in the next patch.

>
> > +
> > +  interrupt-names:
> > +    items:
> > +      - const: dwc_usb3
>
> So just "core"?

I'd prefer to stick to "dwc_usb3" as that's
1. more expressive by referring to the underlying IP name,
2. consistent with established dwc3 bindings such as
    Documentation/devicetree/bindings/usb/snps,dwc3.yaml,
    Documentation/devicetree/bindings/usb/qcom,snps-dwc3.yaml,
unless you have a strong preference for the alternative naming.

>
> > +      - const: hs_pme
> > +      - const: ss_pme
> > +
> > +  clocks:
> > +    items:
> > +      - description: Non-sticky module clock.
> > +      - description: Sticky module clock.
> > +      - description: USB2 PHY APB clock.
>
> This looks wrong. This is not the USB2 phy, so how can it consume APB clock?

That's a fair point, I'll look into the necessity and placement of this specific
clk/reset and get back.

Thanks,
Roy Luo

>
> > +
> > +  clock-names:
> > +    items:
> > +      - const: non_sticky
> > +      - const: sticky
> > +      - const: u2phy_apb
> > +
> > +  resets:
> > +    items:
> > +      - description: Non-sticky module reset.
> > +      - description: Sticky module reset.
> > +      - description: USB2 PHY APB reset.
>
> This as well.
>
> > +      - description: DRD bus reset.
> > +      - description: Top-level reset.
> > +
> > +  reset-names:
> > +    items:
> > +      - const: non_sticky
> > +      - const: sticky
> > +      - const: u2phy_apb
> > +      - const: drd_bus
> > +      - const: top
>
>
> Best regards,
> Krzysztof