PROCESSOR-SDK-AM62X: Can I used uboot commands to copy u-boot to eMMC?

Hello,

Patricia Holden said:

Is the "mmc write" or "fatwrite mmc" the way to go to do this?

The "mmc write" is for doing RAW writes while "fatwrite mmc" is for writing files to FAT partition.

You may run "help <command>" for the supported subcommands and their syntaxes.

=> help mmc
mmc - MMC sub system

Usage:
mmc info - display info of the current MMC device
mmc read addr blk# cnt
mmc write addr blk# cnt
mmc erase blk# cnt
mmc rescan [mode]
mmc part - lists available partition on current mmc device
mmc dev [dev] [part] [mode] - show or set current mmc device [partition] and set mode
  - the required speed mode is passed as the index from the following list
    [MMC_LEGACY, MMC_HS, SD_HS, MMC_HS_52, MMC_DDR_52, UHS_SDR12, UHS_SDR25,
    UHS_SDR50, UHS_DDR50, UHS_SDR104, MMC_HS_200, MMC_HS_400, MMC_HS_400_ES]
mmc list - lists available devices
mmc wp [PART] - power on write protect boot partitions
  arguments:
   PART - [0|1]
       : 0 - first boot partition, 1 - second boot partition
         if not assigned, write protect all boot partitions
mmc hwpartition <USER> <GP> <MODE> - does hardware partitioning
  arguments (sizes in 512-byte blocks):
   USER - <user> <enh> <start> <cnt> <wrrel> <{on|off}>
        : sets user data area attributes
   GP - <{gp1|gp2|gp3|gp4}> <cnt> <enh> <wrrel> <{on|off}>
        : general purpose partition
   MODE - <{check|set|complete}>
        : mode, complete set partitioning completed
  WARNING: Partitioning is a write-once setting once it is set to complete.
  Power cycling is required to initialize partitions after set to complete.
mmc bootbus <dev> <boot_bus_width> <reset_boot_bus_width> <boot_mode>
 - Set the BOOT_BUS_WIDTH field of the specified device
mmc bootpart-resize <dev> <boot part size MB> <RPMB part size MB>
 - Change sizes of boot and RPMB partitions of specified device
mmc partconf <dev> [[varname] | [<boot_ack> <boot_partition> <partition_access>]]
 - Show or change the bits of the PARTITION_CONFIG field of the specified device
   If showing the bits, optionally store the boot_partition field into varname
mmc rst-function <dev> <value>
 - Change the RST_n_FUNCTION field of the specified device
   WARNING: This is a write-once field and 0 / 1 / 2 are the only valid values.
mmc setdsr <value> - set DSR register value

Regards,

Prashant

Thanks for the quick response!  So is it possible to use "mmc write" to basically clone the u-boot image itself to eMMC gpt "boot" partition?

Patricia Holden said:

So is it possible to use "mmc write" to basically clone the u-boot image itself to eMMC gpt "boot" partition?

No, the "boot" is a GPT partition. You should format it as a FAT partition and then use "fatwrite mmc" from U-Boot to write the U-Boot images.

However, please note this will be of no use because the AM62x ROM doesn't support booting from the GPT partition table. It has support for MBR partition table only.

So, you should flash the different images as follows:

• U-Boot images (tiboot3.bin/tispl.bin/u-boot.img) => Flash these images to eMMC Boot0 partition using "mmc write" from U-Boot.
• Linux Kernel rootfs => Flash it to the created rootfs partition. U-Boot can load the Linux Kernel from both GPT & MBR partitions.

You may refer to the following FAQ as well:

e2e.ti.com/.../faq-sk-am62-how-to-flash-emmc-using-usb-dfu-on-am62x-sk-e2

DFU doesn't seem to work with this custom board.  I could never get it going with the Beagleplay EVM either because I had no access to bootmode pins.

Is there a u-boot command to format the mmc as a FAT partition?

The article here says I can't format the boot partition as FAT using uboot:  https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1368935/am6411-unable-to-use-the-u-boot-shell-to-create-fat-partitions-in-the-emmc.

So how do I format the partition as FAT per your suggestion?

Thanks!

Patricia Holden said:

So how do I format the partition as FAT per your suggestion?

I also suggested that even if you could format and flash the U-Boot images, it will be of no use unless you are using the MBR partition table.

In any case, you may boot to Linux to format the partition using mkfs, mount, and then simply copy the images. Otherwise, you may also create the FAT filesystem image on your PC and flash it as a RAW image to the FAT partition.

You should keep only the Linux Kernel in the eMMC UDA partition & flash the U-Boot images to the eMMC Boot0 partition.

Just in case, the eMMC Boot0 is literally a hardware partition & has nothing to do with the logical partition "boot". The eMMC is usually divided into the following hardware partitions: 1) Boot0, 2) Boot1, 3) RPMB, and 4) UDA.

The "boot" and "rootfs" partitions you create previously are logical partitions exist in UDA.

You may refer the eMMC layout here:

software-dl.ti.com/.../UG-Memory.html

I have no means by which I can boot the kernel.  I only have eMMC or USB available as boot options.  We were hoping to be able to use DFU, but are having a hard time getting it up and running.  I'll review the eMMC layout doc you suggested, thanks.

How are you booting to U-Boot for now if you do not have working USB DFU setup?

I am not booting to U-Boot.  I was able to get UART bootmode up and running, but got stuck at how to get uboot onto eMMC once u-boot is running.