Re: [PATCH] dt: arm64: qcom: sc8280xp-blackrock: amend usb0-sbu-mux enable gpio

[Dmitry Baryshkov]

On Mon, Jun 09, 2025 at 10:53:56PM +0200, Jens Glathe via B4 Relay wrote:
> From: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx>
> 
> The usb0 port didn't switch to dp altmode, investigation into DSDT
> UCS0 device resulted into GPIO 100.
> 
> Signed-off-by: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> This patch amends the enable gpio for the usb0-sbu-mux to the one
> found in the DSDT file for this box. It shows a list of GPIOs in 
> a certain order, and it has 2 buffers with conflicting values. 
> The one deviating is in the second buffer, at the place where one 
> would expect the GPIO for the select pin of USB0 (by pattern 
> application from USB1). The GPIO previously used is also there, but 
> at the end of the UCS0 buffer structure). Changing it resulted in 
> a working dp altmode functionality on usb0.
> 
> This debug effort is a result of work / testing of the 4-lanes patch
> [1] on all available devices. Independent of it, it enables dp 
> altmode on usb0, and with it, also 4 lanes, making it even more useful.
> 
> [1]: https://lore.kernel.org/all/20250527-topic-4ln_dp_respin-v3-0-f9a0763ec289@xxxxxxxxxxxxxxxx/
> ---
>  arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>

P.S. Might it be that you need to set both GPIOs? Might the other GPIO
be related to USB4 tunnelling?

-- 
With best wishes
Dmitry