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

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Message-ID: <CACr-zFDUAiT7Rd7joV13aZUGCuDrDETeALpESmbp9TYgMOqSww@mail.gmail.com>
Date: Thu, 14 Aug 2025 20:56:30 +0100
From: Christopher Obbard <christopher.obbard@...aro.org>
To: Stephan Gerhold <stephan.gerhold@...aro.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, Johan Hovold <johan@...nel.org>, 
	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

Hi Stephan,

On Thu, 14 Aug 2025 at 15:47, Stephan Gerhold
<stephan.gerhold@...aro.org> wrote:
>
> On Thu, Aug 14, 2025 at 04:21:09PM +0200, Neil Armstrong wrote:
> > On 09/08/2025 00:28, Christopher Obbard wrote:
> > > 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;
> >
>
> I sent a patch fixing this for all the X1 devices upstream earlier [1],
> so you could also just send v7 with just the second patch of your
> series.

Sure. I will do so and base my next version on your patchset.


> The bias-disable is really somewhat device-specific (what if there is no
> pull down on the device side and someone disconnects the panel
> entirely?), so I put it into each board DT separately like Johan
> requested on v5. We have the same for the PCIe pinctrl.
>
> Thanks,
> Stephan
>
> [1]: https://lore.kernel.org/linux-arm-msm/20250814-x1e80100-add-edp-hpd-v1-0-a52804db53f6@linaro.org/T/