linux-kernel - Re: [PATCH v3 2/2] arm64: dts: qcom: x1e80100-yoga: Update panel bindings

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Message-ID: <Zqy0YAj74iM_9zJI@linaro.org>
Date: Fri, 2 Aug 2024 12:26:40 +0200
From: Stephan Gerhold <stephan.gerhold@...aro.org>
To: Rob Clark <robdclark@...il.com>
Cc: linux-arm-msm@...r.kernel.org, Abel Vesa <abel.vesa@...aro.org>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Rob Clark <robdclark@...omium.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: Re: [PATCH v3 2/2] arm64: dts: qcom: x1e80100-yoga: Update panel
 bindings

On Tue, Jul 30, 2024 at 07:26:27AM -0700, Rob Clark wrote:
> On Tue, Jul 30, 2024 at 3:00 AM Stephan Gerhold
> <stephan.gerhold@...aro.org> wrote:
> >
> > On Mon, Jul 29, 2024 at 01:57:25PM -0700, Rob Clark wrote:
> > > From: Rob Clark <robdclark@...omium.org>
> > >
> > > Use the correct panel compatible, and wire up enable-gpio.  It is wired
> > > up in the same way as the x1e80100-crd.
> > >
> > > Signed-off-by: Rob Clark <robdclark@...omium.org>
> > > Reviewed-by: Abel Vesa <abel.vesa@...aro.org>
> > > ---
> > > Note that the power-source differs from the CRD.  Figured that out by
> > > diffing $debugfs/gpio.
> > >
> > >  .../dts/qcom/x1e80100-lenovo-yoga-slim7x.dts    | 17 +++++++++++++++--
> > >  1 file changed, 15 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/arm64/boot/dts/qcom/x1e80100-lenovo-yoga-slim7x.dts b/arch/arm64/boot/dts/qcom/x1e80100-lenovo-yoga-slim7x.dts
> > > index 70977e9fa266..6f8d52c368a4 100644
> > > --- a/arch/arm64/boot/dts/qcom/x1e80100-lenovo-yoga-slim7x.dts
> > > +++ b/arch/arm64/boot/dts/qcom/x1e80100-lenovo-yoga-slim7x.dts
> > > [...]
> > > @@ -669,6 +672,16 @@ &pcie6a_phy {
> > >       status = "okay";
> > >  };
> > >
> > > +&pmc8380_3_gpios {
> > > +     edp_bl_en: edp-bl-en-state {
> > > +             pins = "gpio4";
> > > +             function = "normal";
> > > +             power-source = <0>; /* 1.8V */
> >
> > Hm, are you sure the firmware sets it like this?
> >
> > power-source = <0> is typically VPH, i.e. the main battery supply
> > voltage or similar. This will definitely be higher than 1.8V. It seems a
> > bit odd to use a variable voltage source for a GPIO...
> 
> :shrug:
> 
> Board level stuff is a bit outside my area of expertise, but it's what
> made /sys/kernel/debug/gpio match for gpiochip3 gpio4 and it's what
> made the panel work.  Using <1> resulted in a black screen.
> 
> AFAIU Srini has a yoga 7x as well, and perhaps knows how to read ACPI
> better than I do, so maybe he can double check.
> 

It looks like you're right, I think ACPI also configures power-source = <0>.
Can you just remove the 1.8V comment then? I'm pretty sure it's not 1.8V.

Thanks,
Stephan