[FAQ] J784S4XEVM: How to enable main domain watchdog?

Hello,

Watchdog enabling needs 3 main modules:

1. Watchdog driver & DT nodes
2. SOC ESM
3. PMIC ESM

#2 & #3 are enabled in U-Boot.
#1 is enabled in Linux.

This is the wiring to route the Main domain ESM events(including watchdog) to PMIC.

So j784s4 has 3 instances of ESM. Main, MCU & WKUP domain ESM
respevtively. For the main domain ESM event to propagate to
PMIC the event needs to be routed via MCU ESM & then MCU ESM
needs to route the event to WKUP ESM & finally to PMIC.

MAIN ESM --> MCU ESM --> WKUP ESM --> PMIC.

Below is the patch set on top of 8.6 SDK U-Boot directory:

3531.j784s4-u-boot-esm.tar

Steps to compile U-Boot with ESM support & install to SD card:

cd $PSDK_Linux/board-support/u-boot-2021.01+gitAUTOINC+62a9e51344-g62a9e51344
tar xvf j784s4-u-boot-esm.tar
git am j784s4-u-boot-esm/*
cd ../..
make u-boot
cp board-support/k3-image-gen-2022.01/tiboot3.bin board-support/u-boot_build/a72/tispl.bin board-support/u-boot_build/a72/u-boot.img /media/$USER/boot

The Linux RTI watchdog DTS nodes addition patch here:

0001-arm64-dts-ti-k3-j784s4-main-Enable-the-Main-domain-R.patch

Download the above patch to Linux folder of the SDK.

cd $PSDK_Linux/board-support/linux-5.10.162+gitAUTOINC+76b3e88d56-g76b3e88d56
git am 0001-arm64-dts-ti-k3-j784s4-main-Enable-the-Main-domain-R.patch
cd ../..
make linux-dtbs
sudo make linux-dtbs_install

With that the watchdog reset is functional.

Best Regards,
Keerthy