linux-kernel - Re: [PATCH 1/9] arm64: dts: qcom: x1-asus-zenbook-a14: Add missing pinctrl for eDP HPD

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Message-ID: <ubagrwewqqyvdgjmibhqp57x7ttqukqtv6ziftwsayuomlght6@j2k7i63rldsd>
Date: Mon, 18 Aug 2025 13:33:43 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Stephan Gerhold <stephan.gerhold@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Aleksandrs Vinarskis <alex.vinarskis@...il.com>,
        Abel Vesa <abel.vesa@...aro.org>, Xilin Wu <wuxilin123@...il.com>,
        Jens Glathe <jens.glathe@...schoolsolutions.biz>,
        Srinivas Kandagatla <srini@...nel.org>,
        Sibi Sankar <quic_sibis@...cinc.com>,
        Rajendra Nayak <quic_rjendra@...cinc.com>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        Christopher Obbard <christopher.obbard@...aro.org>
Subject: Re: [PATCH 1/9] arm64: dts: qcom: x1-asus-zenbook-a14: Add missing
 pinctrl for eDP HPD

On Mon, Aug 18, 2025 at 09:44:36AM +0200, Stephan Gerhold wrote:
> On Sat, Aug 16, 2025 at 01:06:50AM +0300, Dmitry Baryshkov wrote:
> > On Thu, Aug 14, 2025 at 03:30:28PM +0200, Stephan Gerhold wrote:
> > > At the moment, we indirectly rely on the boot firmware to set up the
> > > pinctrl for the eDP HPD line coming from the internal display. If the boot
> > > firmware does not configure the display (e.g. because a different display
> > > is selected for output in the UEFI settings), then the display fails to
> > > come up and there are several errors in the kernel log:
> > > 
> > >  [drm:dpu_encoder_phys_vid_wait_for_commit_done:544] [dpu error]vblank timeout: 80020041
> > >  [drm:dpu_kms_wait_for_commit_done:524] [dpu error]wait for commit done returned -110
> > >  [drm:dpu_encoder_frame_done_timeout:2715] [dpu error]enc40 frame done timeout
> > >  ...
> > > 
> > > Fix this by adding the missing pinctrl for gpio119 (func1/edp0_hot and
> > > bias-disable according to the ACPI DSDT).
> > > 
> > > Fixes: 6516961352a1 ("arm64: dts: qcom: Add support for X1-based Asus Zenbook A14")
> > > Signed-off-by: Stephan Gerhold <stephan.gerhold@...aro.org>
> > > ---
> > >  arch/arm64/boot/dts/qcom/x1-asus-zenbook-a14.dtsi | 9 +++++++++
> > >  1 file changed, 9 insertions(+)
> > > 
> > > diff --git a/arch/arm64/boot/dts/qcom/x1-asus-zenbook-a14.dtsi b/arch/arm64/boot/dts/qcom/x1-asus-zenbook-a14.dtsi
> > > index 16d045cf64c08c02c420787e000f4f45cfc2c6ff..613c675aac296f931293a1ba3d8506c6663bad21 100644
> > > --- a/arch/arm64/boot/dts/qcom/x1-asus-zenbook-a14.dtsi
> > > +++ b/arch/arm64/boot/dts/qcom/x1-asus-zenbook-a14.dtsi
> > > @@ -1001,6 +1001,9 @@ &mdss_dp1_out {
> > >  &mdss_dp3 {
> > >  	/delete-property/ #sound-dai-cells;
> > >  
> > > +	pinctrl-0 = <&edp_hpd_default>;
> > > +	pinctrl-names = "default";
> > > +
> > >  	status = "okay";
> > >  
> > >  	aux-bus {
> > > @@ -1236,6 +1239,12 @@ cam_indicator_en: cam-indicator-en-state {
> > >  		bias-disable;
> > >  	};
> > >  
> > > +	edp_hpd_default: edp-hpd-default-state {
> > > +		pins = "gpio119";
> > > +		function = "edp0_hot";
> > > +		bias-disable;
> > > +	};
> > 
> > I think this is common enough. Let's maybe push this into the SoC dtsi
> > instead of copying it to all devices?
> > 
> 
> I had it there before, but Johan commented on the patch set from Chris
> that he would prefer to keep the potentially board-specific pinctrl out
> of the SoC dtsi [1]. So I can either address his feedback or yours. :-)
> 
> There isn't really a convention for X1E either - we have a wild mix
> where some pinctrl is defined in the SoC dtsi (UART, I2C, SDHCI, ...)
> and others is copied for each board (e.g. PCIe).

PCIe pinctrl is a part of SoC DTSI for SM8[4567]0.

> The reason I chose this approach is that I didn't feel it is guaranteed
> that the HPD pin has external pull down. It seems to be the case on most
> devices, but in theory a device could maybe rely on the internal pull
> down. Might be better to have it explicitly defined, the 5 additional
> lines are not that much at the end.

I don't think anybody will use internal pull-down for this, it would be
too risky in case the eDP cable is bad. I have checked several laptops,
they use external pull-down or two MOSFETs.

> I'm also fine with moving it. Perhaps Bjorn or Konrad could comment if
> they would prefer to have the pinctrl template defined in the SoC dtsi?

-- 
With best wishes
Dmitry