flash u-boot from uboot using ums

[razriel]

I have imx8mn evk board.

I want to be able to test changes in u-boot.   I prefer to flash u-boot only to save cycle time instead of flashing the full image.

I am using the ums from the bootloader and able to see boot and rootfs partitions of the emmc on my host/build machine by running ums 0 mmc 2

the u-boot image is not located in the boot partition. I believe its in a known address in the emmc.

I guess I should be able to do a dd command with if=my new u-boot image, of =/dev/mmc and a known offset. can someone confirm its possible. and give me the offsest address and block size.

BR,

Roy 

[razriel]

thanks. it worked.

now I am able to see my changes in the print.

[dvlogic]

I've done that when I was developing my custom u-boot.  The dd command is as follows:

dd if=imx-boot of=/dev/imxdisk bs=1k seek=32 conv=fsync

where my /dev/imxdisk is the mounted USB drive exposed by the ums mmc 2 command (Auto-mounted using the following udev rule)

KERNEL=="sd[b-z]", SUBSYSTEM=="block", ATTRS{idVendor}=="0525", ATTRS{idProduct}=="a4a5", ACTION=="add", \
MODE="0666", SYMLINK+="imxdisk"

[joanxie]

you can refer to the linux user guide, which includes detailed information about this

[razriel]

Can you please add page or chapter in the guide ? I was checking it and could not find.

[joanxie]

I mean download images to the board by uuu or dd command, you can refer to the user guide, for ums, you can refer to the link as below:

"https://developer.technexion.com/docs/using-u-boots-ums-command-to-write-flash-storage-over-usb-otg"

[razriel]

I am still unable to see changes I have created in u-boot running

I am doing the followng procedure:

1. creating patch file to be called by bbappend file of my custom u-boot in yocto.

2. the patch file print another printf line in SPL part of "DDRINFO: ddr init"

3. running bitbake imx-image-core

4. verifying source code of u-boot is changed in build/tmp/work/.../git/drivers/ddr_init.c

5. running ums 0 emmc 2 in u-boot terminal

6. running sudo dd if=imx-boot of=/dev/sda bs=1k seek=32 conv=fsync in my ununtu build machine

getting message write is succefull ~1.8 MB in ~0.3 seconds

7. Ctrl C to stop ums in u-boot consloe and running reset command.

8. u-boot loads again with no print new print

what am I doing wrong ? 

Thanks,

Roy

[dvlogic]

You probably need to change the boot configuration to boot from main eMMC instead of the special boot part.  I'm not in front of my board but I think its the following command 

mmc partconf 2 0 0 0

(I think without the parameters the mmc partconf may show you the current settings too)

[razriel]

this is what I get

u-boot=> mmc partconf 2
EXT_CSD[179], PARTITION_CONFIG:
BOOT_ACK: 0x0
BOOT_PARTITION_ENABLE: 0x1
PARTITION_ACCESS: 0x0

can you please explain more about mmc partconf. 

when I flash the full image in download mode where to u-boot is flashed ?

what actully happend when I did the dd to seek=32  ? it was written to another location ?

this issue is not clear to me and I cannot find much information about it  in the linux user manual.

Thanks

Roy

[dvlogic · Accepted solution]

The dd command will write into the main raw eMMC memory partition area.  The eMMC will also have a boot partition.  I believe when you use the uuu command, it will write the u-boot into the boot partition and enable it in the eMMC part configuration.

u-boot=> mmc partconf 2
EXT_CSD[179], PARTITION_CONFIG:
BOOT_ACK: 0x0
BOOT_PARTITION_ENABLE: 0x1
PARTITION_ACCESS: 0x0

The second 0 in the "mmc partconf 2 0 0 0" will disable the eMMC from booting from the boot partition and instead boot from the main partition. 

Hope this helps - by no means am I an expert, I've just figured most of this out through reading and trial and error.