linux-kernel - Re: [PATCH] arm64: dts: x1e80100-crd: describe HID supplies

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Message-ID: <Zw_tLjudvbTKGAMM@linaro.org>
Date: Wed, 16 Oct 2024 18:43:26 +0200
From: Stephan Gerhold <stephan.gerhold@...aro.org>
To: Abel Vesa <abel.vesa@...aro.org>,
	Johan Hovold <johan+linaro@...nel.org>
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
Subject: Re: [PATCH] arm64: dts: x1e80100-crd: describe HID supplies

On Tue, Oct 15, 2024 at 04:41:13PM +0300, Abel Vesa wrote:
> On 24-10-15 14:24:27, Johan Hovold wrote:
> > Add the missing HID supplies to avoid relying on other consumers to keep
> > them on.
> > 
> > This also avoids the following warnings on boot:
> > 
> > 	i2c_hid_of 0-0010: supply vdd not found, using dummy regulator
> > 	i2c_hid_of 0-0010: supply vddl not found, using dummy regulator
> > 	i2c_hid_of 1-0015: supply vdd not found, using dummy regulator
> > 	i2c_hid_of 1-0015: supply vddl not found, using dummy regulator
> > 	i2c_hid_of 1-003a: supply vdd not found, using dummy regulator
> > 	i2c_hid_of 1-003a: supply vddl not found, using dummy regulator
> > 
> > Note that VREG_MISC_3P3 is also used for things like the fingerprint
> > reader which are not yet fully described so mark the regulator as always
> > on for now.
> > 
> > Fixes: d7e03cce0400 ("arm64: dts: qcom: x1e80100-crd: Enable more support")
> > Cc: Abel Vesa <abel.vesa@...aro.org>
> > Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> > ---
> >  arch/arm64/boot/dts/qcom/x1e80100-crd.dts | 34 +++++++++++++++++++++++
> >  1 file changed, 34 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/qcom/x1e80100-crd.dts b/arch/arm64/boot/dts/qcom/x1e80100-crd.dts
> > index 10b28d870f08..4ab7078f76e0 100644
> > --- a/arch/arm64/boot/dts/qcom/x1e80100-crd.dts
> > +++ b/arch/arm64/boot/dts/qcom/x1e80100-crd.dts
> > @@ -288,6 +288,23 @@ vreg_edp_3p3: regulator-edp-3p3 {
> >  		regulator-boot-on;
> >  	};
> >  
> 
> [...]
> 
> >  
> > +&pm8550ve_8_gpios {
> > +	misc_3p3_reg_en: misc-3p3-reg-en-state {
> > +		pins = "gpio6";
> > +		function = "normal";
> > +		bias-disable;
> 
> Maybe output-enable and input-disable are needed. Can you please check?
> 

FWIW, there is a reason behind explicitly describing the intended
direction of the pin for PMIC GPIOs with properties like "output-enable"
or "input-disable": On QC platforms, PMIC GPIOs can be either in "input"
mode, "output" mode, or "input+output" mode. If you don't specify
exactly what you want, then the pinctrl-spmi-gpio driver will only add
to the existing configuration.

For the configuration above this means:

 1. If GPIO6 is disabled or in "output" mode during boot, the resulting
    mode will be "output".

 2. If GPIO6 is in "input" mode during boot, the resulting mode will be
    "input+output".

I don't know if "input+output" mode has any negative impact compared to
pure "output" mode. We usually want to have the pins in a consistent
state though (i.e. independent of the boot up state).

Thanks,
Stephan