Re: [PATCH RFC 1/2] dt-bindings: phy: rockchip-usbdp: add improved ports scheme

From: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
To: Sebastian Reichel <sebastian.reichel@collabora.com>
Cc: Vinod Koul <vkoul@kernel.org>,
	Kishon Vijay Abraham I <kishon@kernel.org>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Heiko Stuebner <heiko@sntech.de>,
	Frank Wang <frank.wang@rock-chips.com>,
	Zhang Yubing <yubing.zhang@rock-chips.com>,
	Andy Yan <andyshrk@163.com>,
	Maud Spierings <maud_spierings@hotmail.com>,
	linux-phy@lists.infradead.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 1/2] dt-bindings: phy: rockchip-usbdp: add improved ports scheme
Date: Sat, 6 Sep 2025 22:24:54 +0300	[thread overview]
Message-ID: <aLyKhngeksG2SKdq@umbar.lan> (raw)
In-Reply-To: <20250904-rock5b-dp-alt-mode-v1-1-23df726b31ce@collabora.com>

On Thu, Sep 04, 2025 at 08:26:02PM +0200, Sebastian Reichel wrote:
> Currently the Rockchip USBDP PHY as a very simply port scheme: It just
> offers a single port, which is supposed to point towards the connector.
> Usually with 2 endpoints, one for the USB-C superspeed port and one for
> the USB-C SBU port.
> 
> This scheme is not good enough to properly handle DP AltMode, so add
> a new scheme, which has separate ports for everything. This has been
> modelled after the Qualcomm QMP USB4-USB3-DP PHY controller binding
> with a slight difference that there is an additional port for the
> USB-C SBU port as the Rockchip USB-DP PHY also contains the mux.
> 
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
> ---
>  .../bindings/phy/phy-rockchip-usbdp.yaml           | 23 ++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/phy/phy-rockchip-usbdp.yaml b/Documentation/devicetree/bindings/phy/phy-rockchip-usbdp.yaml
> index 8b7059d5b1826fdec5170cf78d6e27f2bd6766bb..f728acf057e4046a4d254ee687af3451f17bcd01 100644
> --- a/Documentation/devicetree/bindings/phy/phy-rockchip-usbdp.yaml
> +++ b/Documentation/devicetree/bindings/phy/phy-rockchip-usbdp.yaml
> @@ -114,6 +114,29 @@ properties:
>        A port node to link the PHY to a TypeC controller for the purpose of
>        handling orientation switching.
>  
> +  ports:
> +    $ref: /schemas/graph.yaml#/properties/ports
> +    properties:
> +      port@0:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description:
> +          Output endpoint of the PHY for USB (or DP when configured into 4 lane
> +          mode), which should point to the superspeed port of a USB connector.

What abourt USB+DP mode, where each one gets 2 lanes?

> +
> +      port@1:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description: Incoming endpoint from the USB controller
> +
> +      port@2:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description: Incoming endpoint from the DisplayPort controller
> +
> +      port@3:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description:
> +          Output endpoint of the PHY for DP, which should either point to the
> +          SBU port of a USB-C connector or a DisplayPort connector input port.

I would suggest describing this port as 'DisplayPort AUX signals to be
connected to the SBU port of a USB-C connector (maybe through the
additinal mux, switch or retimer)'. It should not be confused with the
actual DisplayPort signals (as those go through the port@0).

In the Qualcomm world we currently do not describe this link from the
PHY to the gpio-mux or retimer, but I think we will have to do that
soon.

> +
>  required:
>    - compatible
>    - reg
> 
> -- 
> 2.50.1
> 
> 
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip

-- 
With best wishes
Dmitry

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