TDA4VM-Q1: How to save environment variables to the default environment instead of the SD card?

Hi Takuma,

Thanks for your support.

Following the above doc, the kernel file cannot be found after UBoot boot. It needs to reset the values of mmcdev and bootpart to boot properly.

So the customer is currently wondering how to modify the values of mmcdev and bootpart in default env in UBoot?

(SDK version 08.06.00.11)

Thanks and Regards,

Cherry

Hi Cherry,

Apologies for the delay. I can try doing some experiments in the next 2 days and see if I can get you a verified set of instructions to set environment in U-Boot. For now, my assumption is that there are two methods:

1. Running "saveenv" which is a command that is part of default u-boot. There are probably a set of commands to specify offset for where the default environment is saved, and these need to be set to the offset specified in our documentation for "environment" in the eMMC layout section: https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/08_06_00_11/exports/docs/linux/Foundational_Components/U-Boot/UG-Memory.html#booting-tiboot3-bin-tispl-bin-and-u-boot-img-from-emmc-boot-partition-for-k3-class-of-socs

2. Modifying and flashing uEnv.txt. We could make a uEnv.txt file and define these default values in this file. Then flash them to the "environment" location in the eMMC layout section using commands similar to when we flash u-boot.img and other boot binaries.

I plan to try out the above two methods in 2 days and let you know the result. But if you or the customer has bandwidth, please feel free to try this out.

Regards,

Takuma

Hi Cherry,

I was able to set up eMMC boot and would like to share some potential places that one could get stuck at.

Two things:

1. To boot from eMMC, make sure the DIP switches are set to eMMC boot mode from microSD card boot mode. eMMC boot should look like: sw8 1000_0000 sw9 0100_0000
2. For saving environment variable to eMMC,
   1. Add the line changes in the following E2E (I think this thread might have been suggested to you in a separate thread): https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1185260/tda4vm-why-emmc-boot-does-not-take-effect/4464968#4464968
   2. Run "make u-boot"
   3. It will ask for "Environment offset" when building u-boot with the new config additions. For TDA4VM, the offset is 0x680000 for environment variables on eMMC. Ex: Environment offset (ENV_OFFSET) [] (NEW) 0x680000
   4. Reflash the u-boot binaries to microSD card. Ex: sudo cp board-support/u-boot_build/a72/u-boot.img board-support/u-boot_build/a72/tispl.bin board-support/u-boot_build/r5/tiboot3.bin /media/$USER/boot
   5. Reflash eMMC using section 3.1.1.5.5: https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/08_06_00_11/exports/docs/linux/Foundational_Components/U-Boot/UG-Memory.html
   6. After switching DIP switches to eMMC boot mode, should be able to run the "setenv xxxx y" to set environment variable, and running "saveenv" at the end will save environment variables to eMMC. Ex: setenv mmcdev 0
   7. For verification, reboot the board into eMMC boot mode and use printenv to see environment variable. Ex: printenv mmcdev

A recommended documentation to look through when stuck with eMMC would be the following appnote if it has not been recommended already: https://www.ti.com/lit/an/spracy5/spracy5.pdf?ts=1679291807661&ref_url=https%253A%252F%252Fwww.google.com%252F. The appnote goes through the DIP switch settings as well as offsets for where each boot binaries should go.

Please let me know if the customer gets stuck at a step, and share any error logs.

Regards,

Takuma