AM6422: PMIC TI TPS65220 is not initialized in U-Boot

Benjamin Postma

Part Number: AM6422
Other Parts Discussed in Thread: AM6442, TPS65220, TPS65219, SK-AM64B, SK-AM62-LP

Tool/software:

Dear community,

For a custom board we use the AM6442 SOC. As PMIC we use the TI TPS65220, and for ethernet we use two TI DP83822 PHYs.
We want to operate the PHYs with AVD=1.8V. Therefore we connected them to LDO4 (default: 2.5V), which output voltage shall be set to 1.8V (PMIC Vsys=3.3V) as fast as possible after power on.

My observation is that the PMIC is not initialized at all during the boot sequence. Only linux configures the PMIC during kernel boot. I expected that preferably the SPL (R5 or A53), or at least U-Boot initializes all regulators which have the properties "regulator-boot-on;" and "regulator-always-on;" set.

Since the PMIC is initialized by linux, I suppose I have done something wrong in U-Boot.

Here is my the PMIC snippet from my u-boot device tree (which is equal to the device tree used by linux).

&main_i2c0 {
    bootph-all;
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&main_i2c0_pins_default>;
    clock-frequency = <400000>;

    tps65219: pmic@30 {
        bootph-all;
        compatible = "ti,tps65219";
        reg = <0x30>;
        buck1-supply = <&vcc_3v3_sys>;
        buck2-supply = <&vcc_3v3_sys>;
        buck3-supply = <&vcc_3v3_sys>;
        ldo1-supply = <&vcc_3v3>;
        ldo2-supply = <&buck2_reg>;
        ldo3-supply = <&vcc_3v3>;
        ldo4-supply = <&vcc_3v3>;

        pinctrl-names = "default";
        pinctrl-0 = <&pmic_irq_pins_default>;

        interrupt-parent = <&gic500>;                   
        interrupts = <GIC_SPI 224 IRQ_TYPE_LEVEL_HIGH>; 

        regulators {
            buck1_reg: buck1 {
                bootph-all;
                regulator-name = "VDD_CORE";
                regulator-min-microvolt = <750000>;
                regulator-max-microvolt = <750000>;
                regulator-boot-on;
                regulator-always-on;
            };

            buck2_reg: buck2 {
                bootph-all;
                regulator-name = "VCC1V8_SYS";
                regulator-min-microvolt = <1800000>;
                regulator-max-microvolt = <1800000>;
                regulator-boot-on;
                regulator-always-on;
            };

            buck3_reg: buck3 {
                bootph-all;
                regulator-name = "VDD_LPDDR4";
                regulator-min-microvolt = <1100000>;
                regulator-max-microvolt = <1100000>;
                regulator-boot-on;
                regulator-always-on;
            };

            ldo1_reg: ldo1 {
                bootph-all;
                regulator-name = "VDDSHV_SDIO_PMIC";
                regulator-min-microvolt = <1800000>;
                regulator-max-microvolt = <1800000>;
                regulator-always-on;
            };

            ldo2_reg: ldo2 {
                bootph-all;
                regulator-name = "VDDAR_CORE";
                regulator-min-microvolt = <850000>;
                regulator-max-microvolt = <850000>;
                regulator-boot-on;
                regulator-always-on;
            };

            ldo3_reg: ldo3 {
                bootph-all;
                regulator-name = "VDDA_1V8";
                regulator-min-microvolt = <1800000>;
                regulator-max-microvolt = <1800000>;
                regulator-boot-on;
                regulator-always-on;
            };

            ldo4_reg: ldo4 {
                bootph-all;
                regulator-name = "VDD_PHY_1V8";
                regulator-min-microvolt = <1800000>;
                regulator-max-microvolt = <1800000>;
                regulator-boot-on;
                regulator-always-on;
            };
        };
    };
};

I also have a u-boot.dtsi entry (not sure if I need it):

&pmic_irq_pins_default {
    bootph-all;
};

&ldo4_reg{
    regulator-init-microvolt = <1800000>;
};

Here are settings in my a53 defconfig:

CONFIG_DM_PMIC=y
CONFIG_PMIC_TPS65219=y
CONFIG_DM_REGULATOR=y
CONFIG_DM_REGULATOR_TPS65219=y

Here are settings in my r5 defconfig:

CONFIG_DM_REGULATOR=y
CONFIG_SPL_DM_REGULATOR=y
CONFIG_DM_REGULATOR_GPIO=y
CONFIG_SPL_DM_REGULATOR_GPIO=y

So why doesn't u-boot initialize the PMIC? The SK-AM64B has a PMIC, but it is not configured at all during boot, since the output voltages are correct by default.

Any help is appreciated.

BR Benjamin

8 months ago

0 Anshu Madwesh 8 months ago

TI__Mastermind 18985 points

Hi Benjamin,

I'm not exactly sure if this is an issue with the I2C bus or the PMIC itself.

Here a few tests that could be tried:

Is there another I2C device on the custom board that could be accessed at U-Boot? Lets try to access that device. If that device cannot be initialized too, then I'm thinking its an I2C issue.
On the SK-AM64B EVM, there are a few other I2C devices and we can try to access any of them. See the image below.
Add the PMIC node to the U-Boot device tree using the SK-AM64B. You mentioned that its supply voltages are pre-configured, but make a small change (if possible) to see if the change is reflected.

I2C Tree for SK-AM64B:

From searching around, here are a few examples of using the TPS65219 in U-Boot:

SK-AM62-LP EVM: https://git.ti.com/cgit/ti-u-boot/ti-u-boot/tree/arch/arm/dts/k3-am62-lp-sk.dts?h=ti-u-boot-2024.04#n161
Verdin's SOM using AM62: https://git.ti.com/cgit/ti-u-boot/ti-u-boot/tree/arch/arm/dts/k3-am62-verdin.dtsi?h=ti-u-boot-2024.04#n1043
Phycore's SOM using Am62: https://git.ti.com/cgit/ti-u-boot/ti-u-boot/tree/arch/arm/dts/k3-am62-phycore-som.dtsi?h=ti-u-boot-2024.04#n198
AM62 Beagleplay: https://git.ti.com/cgit/ti-u-boot/ti-u-boot/tree/arch/arm/dts/k3-am625-beagleplay.dts?h=ti-u-boot-2024.04#n661

Best Regards,

Anshu

0 Benjamin Postma 8 months ago in reply to Anshu Madwesh

Prodigy 70 points

Hi Anshu,

thank you for your fast supply. I do not think that it is an I2C issue, since when I interrupt the boot process and enter U-Boot cmdline, I can communicate with the PMIC using the u-boot commands pmic and regulator. I even can adust the voltage of LDO4 manually to 1800000uV as it is specified in the device tree node (using command regulator).

Can you confirm that u-boot (or SPL?) should initialize the PMIC without further actions like writing some code in my board.c?

I had a look at the device tree nodes of the other boards as well, and I don't see any big difference, aside from the properties

ti,power-button and system-power-controller. 



BR Benjamin

0 Anshu Madwesh 8 months ago in reply to Benjamin Postma

TI__Mastermind 18985 points

Hi Benjamin,

Apologies for the delay as I had high priority work to do. I wouldn't expect U-Boot or SPL to directly configure the PMIC, rather it would only initialize the I2C bus that its connected to.

Can help me understand the use case to communicating to the PMIC during the boot process? You mentioned that the Ethernet PHYs need to be powered on but why does it need to be done prior to Linux booting?

Thanks,
Anshu

0 Benjamin Postma 8 months ago in reply to Anshu Madwesh

Prodigy 70 points

Hi Anshu,

no worries. From the docs (doc/device-tree-bindings/regulator/regulator.txt · master · U-Boot / U-Boot · GitLab) I would expect that all regulator with the property "regulator-boot-on" set will be initialized as early as possible. To me it seems correct to have all regulators configured as early as possible during the boot sequence.

In case of the PHY, we probably want to use ethernet from u-boot (during production). Therefore it would be good that the PHYs operate with a correct supply voltage for AVD. Since only 1.8V and 3.3V are supported, and LDO4 output voltage is 2.5V per default, we want to change the output voltage during SPL or U-Boot boot, preferably automatically done by the driver.

If this is not done automatically, I guess I could do it in my board.c file, but I wonder what the mentioned property is then for.

At least if I set the property regulator-init-microvolt, the driver should set the voltage, if I read regulator-uclass.c (u-boot/drivers/power/regulator/regulator-uclass.c at master · u-boot/u-boot · GitHub) correctly.

if (uc_pdata->flags & REGULATOR_FLAG_AUTOSET_UV)
		ret = regulator_set_value(dev, uc_pdata->min_uV);
	if (uc_pdata->init_uV > 0)
		ret = regulator_set_value(dev, uc_pdata->init_uV);

BR Benjamin

0 Anshu Madwesh 8 months ago in reply to Benjamin Postma

TI__Mastermind 18985 points

Hi Benjamin,

Just to confirm my understanding of the background. The expectation:

The processor (prior to u-boot) tells the PMIC via i2c to turn on LDO4 and set it to the required voltage. This LDO4 is used to supply power to the Ethernet PHY so it can be used during u-boot.

One question: Is it possible to pre-program the PMIC register to enable the LDO4? In case the LDO4 needs to be changed after U-Boot, it should be able to.

I'm not very familiar with those regulator docs so I'll need some time to look into them.

Thanks,

Anshu

0 Benjamin Postma 7 months ago in reply to Anshu Madwesh

Prodigy 70 points

Hi Anshu,

sorry for my delayed response. My expectation was that the SPL running from R5 processor (see appended image) initializes the PMIC according to the device tree, but this didn't work.

Programming the PMIC during manufacturing would be possible, but introduces further complexity, so we would like to avoid it. Since we do not have high volumes, ordering a pre-configured variant seems not to be an option.

So we decided to connect the PHYs to LDO3, which is configured to 1.8V per default on startup, which solves our problem as well.

BR Benjamin

0 Anshu Madwesh 7 months ago in reply to Benjamin Postma

TI__Mastermind 18985 points

Thanks for the update Benjamin. This thread will be closed for now. Feel free to create a new post for any other questions.

Thanks,

Anshu

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AM6422: PMIC TI TPS65220 is not initialized in U-Boot