linux-kernel - Re: [PATCH v4 1/2] dt-bindings: phy: google: Add Google Tensor G5 USB PHY

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Message-ID: <CA+zupgwQTLEs8_7i-VsGbGV7O2Y3XFA1C3aV7iuv2HLOwKns3w@mail.gmail.com>
Date: Thu, 23 Oct 2025 15:22:31 -0700
From: Roy Luo <royluo@...gle.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, Peter Griffin <peter.griffin@...aro.org>, 
	André Draszik <andre.draszik@...aro.org>, 
	Tudor Ambarus <tudor.ambarus@...aro.org>, Joy Chakraborty <joychakr@...gle.com>, 
	Naveen Kumar <mnkumar@...gle.com>, Badhri Jagan Sridharan <badhri@...gle.com>, linux-phy@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v4 1/2] dt-bindings: phy: google: Add Google Tensor G5 USB PHY

On Wed, Oct 22, 2025 at 11:43 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> On Fri, Oct 17, 2025 at 11:51:58PM +0000, Roy Luo wrote:
> > Document the device tree bindings for the USB PHY interfaces integrated
> > with the DWC3 controller on Google Tensor SoCs, starting with G5
> > generation. The USB PHY on Tensor G5 includes two integrated Synopsys
> > PHY IPs: the eUSB 2.0 PHY IP and the USB 3.2/DisplayPort combo PHY IP.
> >
> > Due to a complete architectural overhaul in the Google Tensor G5, the
> > existing Samsung/Exynos USB PHY binding for older generations of Google
> > silicons such as gs101 are no longer compatible, necessitating this new
> > device tree binding.
> >
> > Signed-off-by: Roy Luo <royluo@...gle.com>
> > ---
> >  .../bindings/phy/google,gs5-usb-phy.yaml      | 104 ++++++++++++++++++
> >  1 file changed, 104 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/phy/google,gs5-usb-phy.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/phy/google,gs5-usb-phy.yaml b/Documentation/devicetree/bindings/phy/google,gs5-usb-phy.yaml
> > new file mode 100644
> > index 000000000000..c92c20eba1ea
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/google,gs5-usb-phy.yaml
> > @@ -0,0 +1,104 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +# Copyright (C) 2025, Google LLC
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/phy/google,gs5-usb-phy.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Google Tensor Series (G5+) USB PHY
> > +
> > +maintainers:
> > +  - Roy Luo <royluo@...gle.com>
> > +
> > +description: |
> > +  Describes the USB PHY interfaces integrated with the DWC3 USB controller on
> > +  Google Tensor SoCs, starting with the G5 generation.
> > +  Two specific PHY IPs from Synopsys are integrated, including eUSB 2.0 PHY IP
> > +  and USB 3.2/DisplayPort combo PHY IP.
> > +  The hardware can support three PHY interfaces, which are selected using the
> > +  first phandle argument in the PHY specifier::
>
> Just one ':', anyway this sentence and below does not belong to
> description but to phy-cells. You describe the cells.
>
> Or just mention the header with IDs - here or in phy-cells.
>
> > +    0 - USB high-speed.
> > +    1 - USB super-speed.
> > +    2 - DisplayPort
> > +
> > +properties:
> > +  compatible:
> > +    const: google,gs5-usb-phy
> > +
> > +  reg:
> > +    items:
> > +      - description: USB2 PHY configuration registers.
> > +      - description: USB 3.2/DisplayPort combo PHY top-level registers.
> > +
> > +  reg-names:
> > +    items:
> > +      - const: u2phy_cfg
> > +      - const: dp_top
> > +
> > +  "#phy-cells":
> > +    const: 1
> > +
> > +  clocks:
> > +    items:
> > +      - description: USB2 PHY clock.
> > +      - description: USB2 PHY APB clock.
> > +
> > +  clock-names:
> > +    items:
> > +      - const: usb2_phy
>
> core
>
> > +      - const: u2phy_apb
>
> apb
>

Just to provide the full context, these two clocks/resets
(usb2_phy and u2phy_apb) are specifically for eUSB2 PHY.
USB3/DP combo PHY has its own clock/reset that hasn't
been added yet, we would have to differentiate them once
USB3 support is added in the future.
I'm fine with the suggested name change, and we can
address the naming again when USB3 is ready for
integration.

Regards,
Roy Luo

> > +
> > +  resets:
> > +    items:
> > +      - description: USB2 PHY reset.
> > +      - description: USB2 PHY APB reset.
> > +
> > +  reset-names:
> > +    items:
> > +      - const: usb2_phy
> > +      - const: u2phy_apb
>
> Same here
>
> > +
> > +  power-domains:
> > +    maxItems: 1
>
> Best regards,
> Krzysztof
>