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

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Message-ID: <42df7bb1-c587-429f-88ac-1e5ffa7c2b3f@nvidia.com>
Date: Tue, 13 Jan 2026 14:49:59 +0000
From: Jon Hunter <jonathanh@...dia.com>
To: Diogo Ivo <diogo.ivo@...nico.ulisboa.pt>,
 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 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.

Jon

-- 
nvpublic