linux-kernel - Re: [PATCH 2/2] arm64: dts: qcom: x1p42100-lenovo-thinkbook-16: add hdmi bridge with enable pin

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Message-ID: <26f0ebac-22cf-497f-a013-8211335d085c@oldschoolsolutions.biz>
Date: Sat, 3 Jan 2026 09:53:02 +0100
From: Jens Glathe <jens.glathe@...schoolsolutions.biz>
To: Dmitry Baryshkov <dmitry.baryshkov@....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,
 Val Packett <val@...kett.cool>
Subject: Re: [PATCH 2/2] arm64: dts: qcom: x1p42100-lenovo-thinkbook-16: add
 hdmi bridge with enable pin

On 21.12.25 16:51, Jens Glathe wrote:

> On 21.12.25 16:23, Dmitry Baryshkov wrote:
>> This can't work, the pin can only be used for a single function.
>
> See, that's where I am, too :) Configure it that way and you get the 
> HDMI to work, be prudent and remove edp_hpd_default, and boom the 
> internal display is gone. Maybe someone with some schematics can shed 
> light on this.
>
Well I dived into that again (no schematics, sadly) and found and tested 
something that works through exclusion. In pinctrl-x1e80100.c there is a 
definition for function block goups (?) describing gpio pins intended 
for functions. Well, gpio120 (very near 119) is only and exclusively in 
edp1_hot_groups[] and edp0_lcd_groups[]. edp1_hot_groups[] fits pretty 
well for a second display out, and its not used anywhere. Assigned it as 
enable pin and it works well.

Will do a V2 of this patch, thank you for all the suggestions.

with best regards

Jens