linux-kernel - Re: [PATCH 5/5] arm64: tegra: smaug: Add usb-role-switch support

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Message-ID: <d2f01fe4-f92a-408a-890c-7e37f7c414c3@tecnico.ulisboa.pt>
Date: Tue, 13 Jan 2026 15:11:29 +0000
From: Diogo Ivo <diogo.ivo@...nico.ulisboa.pt>
To: Jon Hunter <jonathanh@...dia.com>, Mathias Nyman
 <mathias.nyman@...el.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Thierry Reding <thierry.reding@...il.com>, JC Kuo <jckuo@...dia.com>,
 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>
Cc: linux-usb@...r.kernel.org, linux-tegra@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
 devicetree@...r.kernel.org
Subject: Re: [PATCH 5/5] arm64: tegra: smaug: Add usb-role-switch support



On 1/13/26 14:49, Jon Hunter wrote:
> 
> On 13/01/2026 14:20, Diogo Ivo wrote:
>>
>>
>> On 1/12/26 22:03, Jon Hunter wrote:
>>>
>>> On 04/12/2025 21:27, Diogo Ivo wrote:
>>>> The USB2 port on Smaug is configured for OTG operation but lacked the
>>>> required 'usb-role-switch' property, leading to a failed probe and a
>>>> non-functioning USB port. Add the property along with setting the 
>>>> default
>>>> role to host.
>>>>
>>>> Signed-off-by: Diogo Ivo <diogo.ivo@...nico.ulisboa.pt>
>>>> ---
>>>>   arch/arm64/boot/dts/nvidia/tegra210-smaug.dts | 2 ++
>>>>   1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/nvidia/tegra210-smaug.dts b/arch/ 
>>>> arm64/boot/dts/nvidia/tegra210-smaug.dts
>>>> index b8d854f90be7..49bf23d6f593 100644
>>>> --- a/arch/arm64/boot/dts/nvidia/tegra210-smaug.dts
>>>> +++ b/arch/arm64/boot/dts/nvidia/tegra210-smaug.dts
>>>> @@ -1809,6 +1809,8 @@ usb2-0 {
>>>>                   status = "okay";
>>>>                   vbus-supply = <&usbc_vbus>;
>>>>                   mode = "otg";
>>>> +                usb-role-switch;
>>>> +                role-switch-default-mode = "host";
>>>>               };
>>>
>>>
>>> This change does add the following warning when building with CHECK_DTBS
>>> ...
>>>
>>> arch/arm64/boot/dts/nvidia/tegra210-smaug.dtb: padctl@...9f000 
>>> (nvidia,tegra210-xusb-padctl): ports:usb2-0: 'role-switch-default- 
>>> mode' does not match any of the regexes: '^pinctrl-[0-9]+$'
>>>      from schema $id: http://devicetree.org/schemas/phy/ 
>>> nvidia,tegra210- xusb-padctl.yaml
>>>
>>> I know that there are many warnings seen for the smaug DTB, but it would
>>> be good to ensure we don't add more.
>>
>> The 'role-switch-default-mode' property is read by the driver to set the
>> initial role for the port [0] and is needed in order for the port to work
>> when booting so in order to fix the warning this property needs to be 
>> added
>> to the binding.
> 
> Correct.
> 
>> As for the other warning ('connector' is a dependency of 'usb-role- 
>> switch')
>> again I think the binding needs to be adjusted since in the Pixel C the
>> connector node should be under the (as for now not present)
>> cros-ec-typec node and the usb2-0 is then modeled as a remote-endpoint
>> for the full connector. I am currently working on fixing the cros-ec- 
>> typec
>> driver and already have a working fix for automatic role switching but
>> in any case I think the binding is what needs changing. If you agree
>> with this then I will add the necessary changes to the DT binding in v2.
> 
> Yes in both cases we need fixes to the DT binding that's all.

Perfect, will do for v2.

Diogo

> Jon
>