linux-kernel - Re: [PATCH v6 1/2] arm64: dts: qcom: x1e78100-t14s: add hpd gpio to dp controller

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Message-ID: <536dd237-e668-4a88-ac2b-3bc88dca8a3e@linaro.org>
Date: Thu, 14 Aug 2025 16:21:09 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Christopher Obbard <christopher.obbard@...aro.org>,
 Johan Hovold <johan@...nel.org>
Cc: Douglas Anderson <dianders@...omium.org>,
 Jessica Zhang <quic_jesszhan@...cinc.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, Rui Miguel Silva <rui.silva@...aro.org>,
 Abel Vesa <abel.vesa@...aro.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH v6 1/2] arm64: dts: qcom: x1e78100-t14s: add hpd gpio to
 dp controller

On 09/08/2025 00:28, Christopher Obbard wrote:
> Hi Johan,
> 
> 
> On Mon, 4 Aug 2025 at 14:13, Johan Hovold <johan@...nel.org> wrote:
>>
>> On Thu, Jul 31, 2025 at 09:51:26PM +0100, Christopher Obbard wrote:
>>> The eDP controller has an HPD GPIO. Describe it in the device tree
>>> for the generic T14s model, as the HPD GPIO is used in both the
>>> OLED and LCD models which inherit this device tree.
>>
>>> @@ -5779,6 +5779,11 @@ tlmm: pinctrl@...0000 {
>>>                        gpio-ranges = <&tlmm 0 0 239>;
>>>                        wakeup-parent = <&pdc>;
>>>
>>> +                     edp_hpd_active: edp-hpd-active-state {
>>
>> The node name and label needs an index as this SoC has two edp hpd pins
>> as I already pointed out.
> 
> Sure. After looking at the schematics this should be called
> edp0_hpd_active. I will fix this in the next revision.
> 
> 
>>> +                             pins = "gpio119";
>>> +                             function = "edp0_hot";
>>
>> And you also need to configure the bias somewhere as you should not rely
>> on the firmware having configured things for you (as I also pointed out
>> before).
>>
>> On my T14s the internal pull-up has been disabled.
> 
> I am still unsure of what else needs to be set here. Can you help me
> with the correct settings?

Just add bias-disable;

Neil

> 
> Thanks,
> Chris