Multiple devices fail dtbs-check with missing regulators for nt36672a panel

[minlexx]

sdm636-asus-x00td.dtb: panel@0 (txd,txdi600yanpa-43v3): 'vddpos-supply' is a required property
sdm636-asus-x00td.dtb: panel@0 (txd,txdi600yanpa-43v3): 'vddneg-supply' is a required property
sdm636-xiaomi-tulip.dtb: panel@0 (tianma,tl063fvmc43-02): 'vddpos-supply' is a required property
sdm636-xiaomi-tulip.dtb: panel@0 (tianma,tl063fvmc43-02): 'vddneg-supply' is a required property
sdm660-xiaomi-jasmine.dtb: panel@0 (tianma,tl060fvxs16-00): 'vddpos-supply' is a required property
sdm660-xiaomi-jasmine.dtb: panel@0 (tianma,tl060fvxs16-00): 'vddneg-supply' is a required property
sdm660-xiaomi-lavender-shenchao.dtb: panel@0 (shenchao,fhdplus-video): 'vddpos-supply' is a required property
sdm660-xiaomi-lavender-shenchao.dtb: panel@0 (shenchao,fhdplus-video): 'vddneg-supply' is a required property
sdm660-xiaomi-lavender-tianma.dtb: panel@0 (tianma,tl063fvmca01-00): 'vddpos-supply' is a required property
sdm660-xiaomi-lavender-tianma.dtb: panel@0 (tianma,tl063fvmca01-00): 'vddneg-supply' is a required property

Choose one of

• make those regulators optional
• if there is no driver for regulators, specify fake regulator-fixed in device trees (would be nice to have sdm660-xiaomi-common.dtsi for that)
• add an actual regulator driver for lcdb/oledb or lab/ibb or whatever is used in downstream

[minlexx]

So in downstream dts panel supplies for all non-OLED panels are described in node https://github.com/LineageOS/android_kernel_xiaomi_sdm660/blob/lineage-18.1/arch/arm/boot/dts/qcom/sdm660-mdss-panels.dtsi#L32:

dsi_panel_pwr_supply: dsi_panel_pwr_supply {
		#address-cells = <1>;
		#size-cells = <0>;

		qcom,panel-supply-entry@0 {
			reg = <0>;
			qcom,supply-name = "wqhd-vddio";
			qcom,supply-min-voltage = <1800000>;
			qcom,supply-max-voltage = <1950000>;
			qcom,supply-enable-load = <32000>;
			qcom,supply-disable-load = <80>;
		};

		qcom,panel-supply-entry@1 {
			reg = <1>;
			qcom,supply-name = "lab";
			qcom,supply-min-voltage = <4600000>;
			qcom,supply-max-voltage = <6000000>;
			qcom,supply-enable-load = <100000>;
			qcom,supply-disable-load = <100>;
		};

		qcom,panel-supply-entry@2 {
			reg = <2>;
			qcom,supply-name = "ibb";
			qcom,supply-min-voltage = <4600000>;
			qcom,supply-max-voltage = <6000000>;
			qcom,supply-enable-load = <100000>;
			qcom,supply-disable-load = <100>;
			qcom,supply-post-on-sleep = <10>;
		};
	};

which is refernced in qcom,panel-supply-entries = ... under each panel node like here

These nodes describe property names with phandles to regulators, and their voltage constraints to set to downstream display/panel driver to enable during probe.

Specific phandle references are not set on panel node, but on dsi controller node: https://github.com/LineageOS/android_kernel_xiaomi_sdm660/blob/lineage-18.1/arch/arm/boot/dts/qcom/sdm660-mdss.dtsi#L373 which are

			wqhd-vddio-supply = <&pm660_l11>;
			vdda-3p3-supply = <&pm660l_l6>;
			lab-supply = <&lcdb_ldo_vreg>;
			ibb-supply = <&lcdb_ncp_vreg>;

vdda-3p3 aka pm660l_l6 is used only in dsi_panel_pwr_supply_labibb_amoled which we can ignore here, since its unused.

wqhd-vddio aka pm660_l11 aka l11a is already specified.

So we lack only lab-supply and ibb-supply which reference the nodes in pm660l.dtsi under https://github.com/LineageOS/android_kernel_xiaomi_sdm660/blob/lineage-20/arch/arm64/boot/dts/vendor/qcom/pm660l.dtsi#L267

pm660l_lcdb: qpnp-lcdb@ec00 {
			compatible = "qcom,qpnp-lcdb-regulator";
			#address-cells = <1>;
			#size-cells = <1>;
			reg = <0xec00 0x100>;
			interrupts = <0x3 0xec 0x1 IRQ_TYPE_EDGE_RISING>;
			interrupt-names = "sc-irq";

			qcom,pmic-revid = <&pm660l_revid>;

			lcdb_ldo_vreg: ldo {
				label = "ldo";
				regulator-name = "lcdb_ldo";
				regulator-min-microvolt = <4000000>;
				regulator-max-microvolt = <6000000>;
			};

			lcdb_ncp_vreg: ncp {
				label = "ncp";
				regulator-name = "lcdb_ncp";
				regulator-min-microvolt = <4000000>;
				regulator-max-microvolt = <6000000>;
			};
		};

these regulators are managed by driver https://github.com/LineageOS/android_kernel_xiaomi_sdm660/blob/lineage-20/drivers/regulator/qpnp-lcdb-regulator.c

looking at which its register layout matches closely the https://elixir.bootlin.com/linux/v6.16.8/source/drivers/regulator/qcom-labibb-regulator.c driver. I wonder if lcdb driver support could be added to existing labibb driver at mainline

[minlexx]

Similarities (top lines from lcdb, after ... from labibb):

#define LCDB_STS1_REG			0x08
...
#define REG_LABIBB_STATUS1		0x08
 #define LABIBB_STATUS1_SC_BIT		BIT(6)
 #define LABIBB_STATUS1_VREG_OK_BIT	BIT(7)

#define LCDB_BST_OUTPUT_VOLTAGE_REG	0x41
#define PM660_BST_OUTPUT_VOLTAGE_MASK	GENMASK(4, 0)
#define BST_OUTPUT_VOLTAGE_MASK		GENMASK(5, 0)
...
#define REG_LABIBB_VOLTAGE		0x41
 #define LABIBB_VOLTAGE_OVERRIDE_EN	BIT(7)
 #define LAB_VOLTAGE_SET_MASK		GENMASK(3, 0)
 #define IBB_VOLTAGE_SET_MASK		GENMASK(5, 0)

#define LCDB_ENABLE_CTL1_REG		0x46
#define MODULE_EN_BIT			BIT(7)
#define HWEN_RDY_BIT			BIT(6)
...
#define REG_LABIBB_ENABLE_CTL		0x46
 #define LABIBB_CONTROL_ENABLE		BIT(7)

#define LCDB_BST_ILIM_CTL_REG		0x4B
#define EN_BST_ILIM_BIT			BIT(7)
#define SET_BST_ILIM_MASK		GENMASK(2, 0)
#define MIN_BST_ILIM_MA			200
#define MAX_BST_ILIM_MA			1600
...
#define REG_LABIBB_CURRENT_LIMIT	0x4b
 #define LAB_CURRENT_LIMIT_MASK		GENMASK(2, 0)
 #define IBB_CURRENT_LIMIT_MASK		GENMASK(4, 0)
 #define LAB_CURRENT_LIMIT_OVERRIDE_EN	BIT(3)
 #define LABIBB_CURRENT_LIMIT_EN	BIT(7)

similar, but not quite.. perhaps just similar hardware?

[minlexx]

I've added some debug patch to downstream android kernel and booted LineageOS with it to see the logs directly from device running android:

lavender:/ # dmesg -w | grep -i LCDB
[    0.136420] LCDB: qpnp_lcdb_parse_dt: Unable to get revid data
[    0.136429] LCDB: qpnp_lcdb_regulator_probe: Failed to parse dt rc=-517
[    0.254773] LCDB: qpnp_lcdb_parse_dt: Unable to get revid data
[    0.254781] LCDB: qpnp_lcdb_regulator_probe: Failed to parse dt rc=-517
[    0.273921] LCDB: qpnp_lcdb_parse_dt: Unable to get revid data
[    0.273949] LCDB: qpnp_lcdb_regulator_probe: Failed to parse dt rc=-517
[    0.281318] LCDB: qpnp_lcdb_parse_dt: Unable to get revid data
[    0.281322] LCDB: qpnp_lcdb_regulator_probe: Failed to parse dt rc=-517
[    0.358821] LCDB: qpnp_lcdb_pmic_config: LCDB wa_flags = 0x 0
[    0.358926] LCDB: qpnp_lcdb_get_voltage: LDO voltage read-back = 5400 mv (0x71 = 0x13)
[    0.359075] LCDB: qpnp_lcdb_get_voltage: LDO voltage read-back = 5400 mv (0x71 = 0x13)
[    0.359140] LCDB: qpnp_lcdb_get_voltage: LDO voltage read-back = 5400 mv (0x71 = 0x13)
[    0.359440] LCDB: qpnp_lcdb_get_voltage: NCP voltage read-back = 5400 mv (0x81 = 0x13)
[    0.359505] LCDB: qpnp_lcdb_get_voltage: NCP voltage read-back = 5400 mv (0x81 = 0x13)
[    0.359553] LCDB: qpnp_lcdb_get_voltage: NCP voltage read-back = 5400 mv (0x81 = 0x13)
[    0.359991] LCDB: qpnp_lcdb_regulator_probe: LCDB module successfully registered! lcdb_en=1 ldo_voltage=5400mV ncp_voltage=5400mV bst_voltage=5500mV
[   34.037618] LCDB: qpnp_lcdb_disable: LCDB disabled
[   60.364955] LCDB: qpnp_lcdb_enable: lcdb enabled successfully!
[   63.603630] LCDB: qpnp_lcdb_disable: LCDB disabled
[   66.242101] LCDB: qpnp_lcdb_enable: lcdb enabled successfully!
[   70.428242] LCDB: qpnp_lcdb_disable: LCDB disabled
[   73.875410] LCDB: qpnp_lcdb_enable: lcdb enabled successfully!
[   77.679792] LCDB: qpnp_lcdb_disable: LCDB disabled

The last few lines with enabled/disabled come from me turning screen on/off and indeed we see downstream actually using this regulator and is turning it off when screen is turning off.