Enabling AMUX_PU1 to adc in pm8994

Products Support DragonBoard 820c
#1

Hi,
@Loic @danielt
I have connected a thermistor to AMUX3 of pm8994, with pull up resistor of 100k connected externally and used qcom-spmi-vadc.c driver. I am getting expected o/p from adc with this setup.
As i see this pull up resistor AMUX_PU1, can be used instead of the external pull up resistor that i have used.
But i couldnt find any documentation explaining how to connect AMUX_PU1 and AMUX3 in dts.
Can someone explain how to do this?

Current dts changes are:

pmic_vadc@3100 {
		compatible = "qcom,spmi-vadc";
		reg = <0x3100>;
		#address-cells = <1>;
		#size-cells = <0>;
		#io-channel-cells = <1>;

		/* Channel Node */
		blsp_exp_ain1{
			reg = <VADC_LR_MUX6_AMUX_THM3>;
		};

		/* Refernce Nodes */
		vadc_ref_1250mv{
			reg = <VADC_REF_1250MV>;
		};

		vadc_ref_625mv{
			reg = <VADC_REF_625MV>;
		};

		vadc_gnd_ref{
			reg = <VADC_GND_REF>;
		};

		vadc_vdd_vadc{
			reg = <VADC_VDD_VADC>;
		};
	};
#2

Have you looked at how pms405.dtsi does it? In particular look at pm_therm1, xo_therm in arch/arm64/boot/dts/qcom/pms405.dtsi

#3

I met the same problem. How did I solve it?

#4

Hey,
Refering arch/arm64/boot/dts/qcom/pms405.dtsi, i added a reference node for pull up.

pmic_vadc@3100 {
		compatible = "qcom,spmi-vadc";
		reg = <0x3100>;
		.
                .
                .
		vadc_vdd_vadc{
			reg = <VADC_VDD_VADC>;
		};
                vadc_pu{
                        reg = <VADC_AMUX_PU1>;
                };
	};

But now there is no voltage drop across the thermistor(measured manually). And the sysfs entry is showing 125000 value always

#5

It is hard to tell from this what the issue could be from that snippet. Can you print all your changes?

#6 
pmic_vadc@3100 {
		compatible = "qcom,spmi-vadc";
		reg = <0x3100>;
		#address-cells = <1>;
		#size-cells = <0>;
		#io-channel-cells = <1>;

		/* Channel Node */
		blsp_exp_ain1{
			reg = <VADC_LR_MUX6_AMUX_THM3>;
		};

		/* Refernce Nodes */
		vadc_ref_1250mv{
			reg = <VADC_REF_1250MV>;
		};

		vadc_ref_625mv{
			reg = <VADC_REF_625MV>;
		};

		vadc_gnd_ref{
			reg = <VADC_GND_REF>;
		};

		vadc_vdd_vadc{
			reg = <VADC_VDD_VADC>;
		};
++              vadc_pu{
++                        reg = <VADC_AMUX_PU1>;
++               };
	};