linux-kernel - Re: [PATCH 2/2] arm64: dts: amlogic: add libretech cottonwood support

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Message-ID: <3e69ae4b-5d9e-42ee-a21e-151de8fbb996@linaro.org>
Date:   Tue, 3 Oct 2023 09:35:59 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     Kevin Hilman <khilman@...libre.com>, Da Xue <da.xue@...retech.co>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH 2/2] arm64: dts: amlogic: add libretech cottonwood support

On 02/10/2023 20:57, Jerome Brunet wrote:
> 
> On Mon 02 Oct 2023 at 18:45, Neil Armstrong <neil.armstrong@...aro.org> wrote:
> 

<snip>

>>> +&usb3_pcie_phy {
>>> +	#address-cells = <1>;
>>> +	#size-cells = <0>;
>>> +	phy-supply = <&vcc_5v>;
>>> +
>>> +	hub: hub@1 {
>>> +		compatible = "usb5e3,626";
>>> +		reg = <1>;
>>> +		reset-gpios = <&gpio GPIOC_7 (GPIO_ACTIVE_LOW | GPIO_OPEN_DRAIN)>;
>>> +	};
>>
>> Not sure the PHY is the right place to put the USB HUB,
>> and it's probable the HUB is connected to both the USB2 and USB3 lines
> 
> It is connected to the USB3.0 only
> 
>> so you should have both USB IDs in DT like it'd done for the Odroid-C4:
>>
>> / {
>> ...
>>           /* USB hub supports both USB 2.0 and USB 3.0 root hub */
>>           usb-hub {
>>                   dr_mode = "host";
>>                   #address-cells = <1>;
>>                   #size-cells = <0>;
>>
>>                   /* 2.0 hub on port 1 */
>>                   hub_2_0: hub@1 {
>>                           compatible = "usb2109,2817";
>>                           reg = <1>;
>>                           peer-hub = <&hub_3_0>;
>>                           reset-gpios = <&gpio GPIOH_4 GPIO_ACTIVE_LOW>;
>>                           vdd-supply = <&vcc_5v>;
>>                   };
>>
>>                   /* 3.1 hub on port 4 */
>>                   hub_3_0: hub@2 {
>>                           compatible = "usb2109,817";
>>                           reg = <2>;
>>                           peer-hub = <&hub_2_0>;
>>                           reset-gpios = <&gpio GPIOH_4 GPIO_ACTIVE_LOW>;
>>                           vdd-supply = <&vcc_5v>;
>>                   };
>>           };
>> ...
>> };
>>
>> if it only has a single USB ID, then it should go under the dwc3 node.
> 
> The usb controller is connected to the PHY and what's coming out of the PHY
> goes to the hub. It seems logical to hub the hub under it.
> 
> Why bypass the PHY ?

The USB bindings the USB devices nodes should be under the controller's node,
not the PHY, see:

Documentation/devicetree/bindings/usb/usb-hcd.yaml
...
patternProperties:
   "^.*@[0-9a-f]{1,2}$":
     description: The hard wired USB devices
     type: object
     $ref: /schemas/usb/usb-device.yaml
...
and the example.

Subnodes aren't allowed in the PHY node.

Neil

> 
>>
>>> +};
>>> +
>>> +&usb {
>>> +	status = "okay";
>>> +};

<snip>