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

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Message-ID: <7283e3e7-54f6-4946-b526-2fa180f15c50@kernel.org>
Date: Thu, 25 Dec 2025 09:33:59 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Shawn Guo <shawnguo@...nel.org>, 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 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.

Best regards,
Krzysztof