Hello,

On Sat, Jul 18, 2026 at 07:06:28PM +0200, Jens Glathe via B4 Relay wrote:
> On Qualcomm X1E80100 platforms (e.g. Lenovo ThinkPad T14s Gen 6)
> using the Parade PS883x retimer, connecting USB4-capable docks such
> as the Lenovo 40B0 via a regular Type-C cable (which forces the dock
> into Type-C fallback mode) often results in working USB but no
> DisplayPort output.
> 
> This series addresses the issue with two main changes:
> 
> - Add a new optional DT property "parade,disable-usb4". When present,
>   the PS883x driver rejects USB4 mode (-EOPNOTSUPP). This forces the
>   Type-C stack to fall back to USB3 + DP Alt Mode, which works
>   reliably with the 40B0.
> 
> - Refactor DP altmode handling to also support the legacy
>   TYPEC_DP_STATE_F request (deprecated since DP Alt Mode 1.0b) sent by
>   the 40B0 and other docks (e.g. SSK SC220).
> 
> - Add a short delay after writing configuration registers, which
>   improves hotplug reliability.
> 
> This is a temporary workaround until full USB4 DP tunneling support is
> available in the X1E USB4 controller and qmp-combo PHY stack.
> 
> Note: The DT patch adds the new property to all currently upstream
> boards using the PS883x retimer (15 files). Happy to split it on v2
> if requested.

I don't think a kernel driver limitation is a good reason for the DT
property. I suggest to add something like this in the ps883x driver
instead:

/*
 * Hamoa does not yet support USB4, disable it for now to gracefully
 * fall back to USB3 + DP AltMode. This should be removed once USB4
 * support landed for X1E.
 */
if (of_machine_is_compatible("qcom,x1e80100"))
    disable_usb4 = true;

Greetings,

-- Sebastian

> As an additional observation, the same dock with type-c cable works well
> on Thinkpad X13s, Thinkbook 16 G7 QOY, Ideapad 5 14Q8X9, but doesn't need
> the ps883x changes (naturally). 
> 
> Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
> ---
> Jens Glathe (5):
>       dt-bindings: usb: parade,ps8830: Add parade,disable-usb4 property
>       usb: typec: ps883x: Return -EOPNOTSUPP for USB4 when parade,disable-usb4 is set
>       usb: typec: mux: ps883x: refactor DP altmode handling and support TYPEC_DP_STATE_F
>       usb: typec: mux: ps883x: add a delay after writing config regs
>       arm64: dts: qcom: x1: disable ps883x USB4 capability
> 
>  .../devicetree/bindings/usb/parade,ps8830.yaml     |  6 +++
>  arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts         |  4 ++
>  .../qcom/hamoa-lenovo-ideacentre-mini-01q8x10.dts  |  2 +
>  arch/arm64/boot/dts/qcom/purwa-iot-evk.dts         |  6 +++
>  arch/arm64/boot/dts/qcom/x1-asus-vivobook-s15.dtsi |  4 ++
>  arch/arm64/boot/dts/qcom/x1-asus-zenbook-a14.dtsi  |  4 ++
>  arch/arm64/boot/dts/qcom/x1-crd.dtsi               |  6 +++
>  arch/arm64/boot/dts/qcom/x1-dell-thena.dtsi        |  4 ++
>  arch/arm64/boot/dts/qcom/x1-hp-omnibook-x14.dtsi   |  2 +
>  arch/arm64/boot/dts/qcom/x1-microsoft-denali.dtsi  |  4 ++
>  arch/arm64/boot/dts/qcom/x1e001de-devkit.dts       |  6 +++
>  .../dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi    |  4 ++
>  .../boot/dts/qcom/x1e80100-dell-xps13-9345.dts     |  4 ++
>  .../boot/dts/qcom/x1e80100-lenovo-yoga-slim7x.dts  |  6 +++
>  .../dts/qcom/x1e80100-medion-sprchrgd-14-s1.dts    |  2 +
>  .../boot/dts/qcom/x1e80100-microsoft-romulus.dtsi  |  4 ++
>  drivers/usb/typec/mux/ps883x.c                     | 47 +++++++++++++++-------
>  17 files changed, 100 insertions(+), 15 deletions(-)
> ---
> base-commit: 0718283ab28bc3907e10b61a6b4be6fefa1cbb2f
> change-id: 20260718-ps883x-disable-usb4-19b0fc13b5ab
> 
> Best regards,
> -- 
> Jens Glathe <jens.glathe@oldschoolsolutions.biz>
> 
> 
>