linux-kernel - Re: [PATCH v3 1/3] dt-bindings: usb: Add binding for WCH CH334/CH335 hub controller

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Message-ID: <07ce7c4e-7fc7-40f8-9c46-4977e3ce2458@cherry.de>
Date: Mon, 12 Jan 2026 15:00:48 +0100
From: Quentin Schulz <quentin.schulz@...rry.de>
To: Chaoyi Chen <kernel@...kyi.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Heiko Stuebner <heiko@...ech.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Jonas Karlman <jonas@...boo.se>, Chaoyi Chen <chaoyi.chen@...k-chips.com>,
 Hsun Lai <i@...insx.cn>, John Clark <inindev@...il.com>,
 Jimmy Hon <honyuenkwun@...il.com>, Dragan Simic <dsimic@...jaro.org>,
 Michael Riesch <michael.riesch@...labora.com>,
 Peter Robinson <pbrobinson@...il.com>, Alexey Charkov <alchark@...il.com>,
 Shawn Lin <shawn.lin@...k-chips.com>,
 Sebastian Reichel <sebastian.reichel@...labora.com>,
 Andy Yan <andy.yan@...k-chips.com>
Cc: devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-usb@...r.kernel.org
Subject: Re: [PATCH v3 1/3] dt-bindings: usb: Add binding for WCH CH334/CH335
 hub controller

Hi Chaoyi,

On 1/12/26 3:28 AM, Chaoyi Chen wrote:
> From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
> 
> The WCH CH334/CH335[0] are USB2.0 protocol compliant 4-port USB HUB
> controller chips, supporting USB2.0 high-speed and full-speed for
> upstream ports, and USB2.0 high-speed 480Mbps, full-speed 12Mbps and
> low-speed 1.5Mbps for downstream ports, supporting not only low-cost STT
> mode (single TT schedules 4 downstream ports in time share), but also
> supports high performance MTT mode (4 TTs each corresponding to 1 port,
> concurrent processing).
> 
> Add a device tree binding for it.
> 
> [0]: https://www.wch-ic.com/downloads/CH334DS1_PDF.html
> 
> Signed-off-by: Chaoyi Chen <chaoyi.chen@...k-chips.com>
> ---
>   .../devicetree/bindings/usb/wch,ch334.yaml    | 65 +++++++++++++++++++
>   1 file changed, 65 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/usb/wch,ch334.yaml
> 
> diff --git a/Documentation/devicetree/bindings/usb/wch,ch334.yaml b/Documentation/devicetree/bindings/usb/wch,ch334.yaml
> new file mode 100644
> index 000000000000..2eeb92f25b4c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/usb/wch,ch334.yaml
> @@ -0,0 +1,65 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/usb/wch,ch334.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: WCH CH334/CH335 USB 2.0 Hub Controller
> +
> +maintainers:
> +  - Chaoyi Chen <kernel@...kyi.com>
> +
> +allOf:
> +  - $ref: usb-hub.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - usb1a86,8091
> +

Which driver does this node bind to? I couldn't quickly find a driver 
which would match this compatible?

> +  reg: true
> +
> +  reset-gpios:
> +    description: GPIO controlling the RESET# pin.
> +
> +  vdd-supply:
> +    description:
> +      The regulator that provides 3.3V core power to the hub.
> +
> +  vdd2-supply:
> +    description:
> +      The regulator that provides 3.3V or 5V power to the hub.
> +

There's v5 and vdd33 as power input, shouldn't we maybe use those names 
instead? How did you come up with vdd/vdd2?

There's also a timing that needs to be respected after a power-on event 
so that the reset has enough time to be performed, c.f. 3.2.1 Power-on 
Reset in the datasheet you linked to in the commit log. How are you 
making sure we wait those (apparently, the wording in the datasheet is 
confusing) 14ms?

Cheers,
Quentin