linux-kernel - Re: [PATCH v2] arm64: dts: qcom: x1e80100-lenovo-yoga-slim7x: add retimers, dp altmode support

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Message-ID: <CAAQ0ZWT=s2BdobfkKuBAhw5H761ZH7uCH70i_UOR+wJ6cjSZJA@mail.gmail.com>
Date: Thu, 25 Dec 2025 11:29:51 +0800
From: Shawn Guo <shawnguo@...nel.org>
To: jens.glathe@...schoolsolutions.biz, Abel Vesa <abel.vesa@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Rob Clark <robdclark@...il.com>, 
	Jos Dehaes <jos.dehaes@...il.com>
Subject: Re: [PATCH v2] arm64: dts: qcom: x1e80100-lenovo-yoga-slim7x: add
 retimers, dp altmode support

On Fri, Apr 18, 2025 at 12:35 AM Jens Glathe via B4 Relay
<devnull+jens.glathe.oldschoolsolutions.biz@...nel.org> wrote:
>
> From: Jens Glathe <jens.glathe@...schoolsolutions.biz>
>
> comparing with CRD and other dts for a more complete support of the 7X
> only retimers, gpios, regulators, dp outputs
>
> Tested-by: Rob Clark <robdclark@...il.com>
> Tested-by: Jos Dehaes <jos.dehaes@...il.com>
> Signed-off-by: Jens Glathe <jens.glathe@...schoolsolutions.biz>
> ---
> This patch adds the required nodes to support DP Altmode on all three type-c
> ports. The definition is derived from the CRD. Since they are all marked 40Gbps,
> I assume there are 3 PS8830 retimers.
> This modification is now for ~8 weeks in my tree with little to no complaints. I
> don't have access to a Yoga Slim 7X, however many people on #aarch64-laptops do
> and some are using this patch.
> ---
> Changes in v2:
> - removed changes not relevant to retimers and dp altmode (thanks Johan)
> - Link to v1: https://lore.kernel.org/r/20250417-slim7x-retimer-v1-1-5813a7835903@oldschoolsolutions.biz
> ---
>  .../boot/dts/qcom/x1e80100-lenovo-yoga-slim7x.dts  | 476 ++++++++++++++++++++-
>  1 file changed, 470 insertions(+), 6 deletions(-)

Hi,

I'm running a Slim7x China variant (Yoga Air 14s) with Debian 13.
While the Debian stock 6.12 kernel works fine to bring up the display
(AMOLED eDP panel), newer kernels like 6.18 loses display during boot.
I can do either of the following to get the display back to work.

- Enable PS883X driver (Yes, CONFIG_TYPEC_MUX_PS883X is missing from
Debian config [1])

OR

- Revert commit 299038d82418 ("arm64: dts: qcom:
x1e80100-lenovo-yoga-slim7x: add retimers, dp altmode support")

My understanding is that a PS883X driver is required only for external
DP support.  Why would the driver missing impact/break the internal
panel support?  Do you guys have any insight on this?  Thanks!

Shawn

[1] https://salsa.debian.org/kernel-team/linux/-/merge_requests/1760