Hi Tamás,
Dear All,
I am trying to implement an automatic firmware upgrade functionality on a U-Boot / embedded Linux board the following way. If anyone has done something similar before, please, comment if this is the right approach to the problem or I should choose a different solution? The hardware is a BeagleBone Black acting as the DFU device (to be updated). It is connected to a host machine (PC) that downloads the new firmware using USB DFU.
So, here are my planned steps for DFU fw upgrade.
- A U-Boot environment variable is set from embedded Linux if a fw
upgrade is required.
I suppose that you have already managed to modify the u-boot envs. When I was extracting the envs to restore them, I've found following script very useful.
cp `find . -name "env_common.o"` copy_env_common.o objcopy -O binary --only-section=.rodata.default_environment `find . -name "copy_env_common.o"` tr '\0' '\n' < copy_env_common.o > default_envs.txt
Here you can modify default_envs.txt
mkenvimage -s 4096 -o params.bin default_envs.txt rm copy_env_common.o default_envs.txt
params.bin should be stored on the medium.
Then the board is rebooted.
- In the boot-up script, U-Boot checks the value of the environment
variable and enters DFU mode instead of booting the Linux kernel. This command is executed to enter DFU mode: 'dfu 0 mmc 0'.
- At this point the host recognises the DFU device and downloads the
new firmware image.
- After the download has finished,
Here since we are polling we need to either press ctrl+C or specify -R with dfu-util command. The problem with -R is that we will reset without executing any commands, so the env will not be reset.
Workaround (as I use it in our boards) is to perform dfu-util -R -aX -D params.bin as the last command.
What presumably you are requiring is to be able to perform: setenv UPDATE "1"; dfu-util -aX -D file1; dfu-util -aX -D file2; setenv UPDATE "0"; reset;
For now I can only propose the above workaround.
However, up till now we are only supporting -R switch, but in the dfu-util (version 0.7) there is the -e/--detach option.
I will investigate if we could use dfu-util -e from host to replace pressing ctrl+C after flashing the device.
the environment variable is reset to indicate normal boot and the board is rebooted.
- Board boots up using the new firmware.
When tested this manually, I found a problem in step 4) because U-Boot requires pressing Ctrl+C after the download finished. This suggests me that DFU can't be controlled by a script as I described above. Is this correct? What is the idea behind waiting for Ctrl+C and not returning immediately?
In the u-boot UDC/gadget is polled and hence we must either specify -R switch at dfu-util or press ctrl-c to end USB transmission and return to target's prompt.
Any comments or hints are appreciated.
Thanks, -Tamás
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