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

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Message-ID: <aU6Ka6elOYfYbflG@dragon>
Date: Fri, 26 Dec 2025 21:15:23 +0800
From: Shawn Guo <shawnguo@...nel.org>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: jens.glathe@...schoolsolutions.biz,
	Abel Vesa <abel.vesa@....qualcomm.com>,
	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 Thu, Dec 25, 2025 at 09:33:59AM +0100, Krzysztof Kozlowski wrote:
> On 25/12/2025 04:29, Shawn Guo wrote:
> > 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])
> 
> Obviously.
> 
> > 
> > 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!
> > 
> 
> You need all drivers to avoid probe deferrals.

Ah, yes!  The display subsystem/card is wired up with all 4 eDP/DP
ports.  A probe failure on any of the ports will cause the display
card fail out, even though the eDP port has all the dependencies in
place.

Shawn