Re: [PATCH 2/5] usb: typec: ps883x: Return -EOPNOTSUPP for USB4 when parade,disable-usb4 is set

[Dmitry Baryshkov]

On Sat, Jul 18, 2026 at 07:06:30PM +0200, Jens Glathe via B4 Relay wrote:
> From: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx>
> 
> On Qualcomm X1E80100 platforms using the Parade PS883x retimer (like
> Lenovo ThinkPad T14s Gen6), hotplugging USB4-capable docks such as the
> Lenovo 40B0 results in working USB but no DisplayPort output on the
> dock's HDMI/DP ports.
> 
> When the dock negotiates USB4, the retimer receives TYPEC_MODE_USB4
> and forwards it via typec_mux_set(). The qmp_combo PHY then selects
> QMPPHY_MODE_USB3_ONLY because no classic DP altmode SVID is present in
> the state, leaving the DP transmitter and AUX channel disabled.

Would it be enough to make QMP combo PHY to treat USB4 as USB3+DP for
the sake of this issue?

> 
> Add a DT property "parade,disable-usb4" that, when present, makes the
> PS883x driver reject USB4 modes as not supported. DP altmode
> configuration is still applied if negotiated, so both USB and
> DisplayPort continue to work.
> 
> This is a temporary workaround until proper USB4 DP tunneling support
> is available in the X1E USB4 controller and qmp_combo PHY stack.
> 

-- 
With best wishes
Dmitry