Configuring PMIC for PVComp

Astra SDK scarthgap_6.12_v2.2 adds support for configuring Power-Voltage Compensation (PVComp) based on the PMIC and Leakage ID. PVComp will adjust the voltages on VCORE and VCPU accordingly. PVComp is implemented in the miniloader for all PMICs supported by our QVL list. The PMIC must be set in the Astra SDK config when building custom boards. This guide covers configuring the PMIC and validating the PVComp functionality.

Note

PVComp based on PMIC is supported on SL16x0 platforms.

Validating PVComp from Serial Console Logs

The Astra Machina RDK board will print the following when the configured PMIC is detected.

Miniloader: tz loader! boot_type(0)
PMIC: Try...
PMIC: VCORE tps6287x (ID: 0x0a), VCPU tps6287x (ID: 0x0a) I2C PMIC detected
set Vcpu from 800000uv to 815000uv
set Vcore from 800000uv to 825000uv

Then set VCORE and VCPU based on the Leakage ID.

RKEK_ID (byte[0:7]) = 0000000000000000
ULT (byte[0:7])     = 4316ebb236e191b5
Leakage ID = 1609
SOCTSEN ID = 105

If the configured PMIC is not detected then the output will look like:

PMIC: Try...
PMIC: Invalid magic number 0x00000000, expected 0x504d4943
PMIC: unknown PMIC model
PMIC: Try again...

Configuring PMIC in Astra SDK configuration

The PMIC is configured in the Astra SDK configution file for the board. Set CONFIG_PMIC_MODE_I2C to y and set CONFIG_VCORE_PMIC_MODEL and CONFIG_VCPU_PMIC_MODEL to the name of the PMIC from the QVL being used.

#
# Preboot Configuration
#
# CONFIG_PREBOOT_MEMORY_MULTIPLE is not set
CONFIG_PMIC_MODE_I2C=y
# CONFIG_PMIC_MODE_PWM is not set
CONFIG_VCORE_PMIC_MODEL="tps6287x"
CONFIG_VCPU_PMIC_MODEL="tps6287x"
# end of Preboot Configuration

Note

Valid PMIC models are m88pg86x, sy8824b, ncp6335d, mp886x, sy8827n, hl7593wl06, tps62868, rt5739, fp6359 and tps6287x.

Validating Functionality

In addition to the log statements, you can also validate the change using a digital multimeter to measure the voltage using the voltage measurement points.

Start by setting the voltage to the maximum value. Run the following command from the Linux prompt.

MAX=$(cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq)
echo $MAX > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
echo $MAX > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq

Observe that the voltage reading on the multimeter shows the maximum voltages.

Next, reboot the system and observe the voltages when the miniloader sets the voltages based on the leakage ID. The voltages should change accordingly.

PMIC: Try...
PMIC: VCORE tps6287x (ID: 0x0a), VCPU tps6287x (ID: 0x0a) I2C PMIC detected
set Vcpu from 900000uv to 750000uv
Vcore is 850000uV, default setting by hardware.

../_images/sl1680-voltage-measurement-points.png — Voltage Measurement Points on SL1680