Re: [PATCH v2] dt: arm64: qcom: sc8280xp-x13s: amend usb0-sbu-mux enable gpio

[Jens Glathe]

On 6/10/25 09:31, Johan Hovold wrote:
> On Tue, Jun 10, 2025 at 07:04:46AM +0200, Jens Glathe via B4 Relay wrote:
> DP alt mode works on both ports of the X13s and "resulted in
> gpio165" makes little sense so this commit message would need to be
> extended.

Well, that was the problem. It didn't on USB0. without and with the 4 
lanes patch.

Observed on Windows Dev Kit 2023 and X13s, what prompted me to look deeper.

> GPIO 101 *is* the OE_N pin, while GPIO 165 is not even connected
> according to the schematics. The mux may still work after this change,
> but you'd be relying on it having been enabled by the boot firmware.
Schematics trump any other data, of course. After a lot of tests and 
some wild
results I could narrow it down to the display I used for testing, iiyama 
XUB2792QSN.
It works with HDMI adapters on ~all other displays I have - with and 
without any
4-lanes, lttpr patches. And the original GPIO. The issue with the 
display appears to
be something linked to how negotiation is done by it on that specific port.

Do I need to do anything since its already NAK?

with best regards

Jens