[FAQ] CCS/TDA4VM: TDA4VM: How to get Console traces on Lauterbach/Trace32 using DCC?

Hi,

DCC: DCC stands Debug communication channel. ARM processors provide very useful utility
to divert all the console prints to a debug channel.  More details here: https://developer.arm.com/documentation/ddi0210/c/Debug-Interface/Debug-Communications-Channel/Communications-through-the-DCC

This is very useful for the following cases:

• No UART instances available on board.
• UART Instances are broken
• UART instance somehow not functional.

Please use the below patch on top of latest 7.0 SDK: 0001-j721e-Enable-DCC-on-T32.patch

The patch does the following:

• Enables the DCC Config option.
• Adds DCC device tree node.
• Add serial3 as dcc alias in device tree.
• Replace stdout-path from UART2(SoC UART) to DCC. So that all the console logs get routed to DCC.
• Lastly adds an infinite loop at the beginning of R5 SPL.

The user needs to compile the u-boot binaries using:

make u-boot
cp board-support/u-boot_build/a53/u-boot.img board-support/u-boot_build/a53/tispl.bin board-support/u-boot_build/r5/tiboot3.bin board-support/prebuilt-images/sysfw.itb /media/$USER/boot/

Open 32 bit arm Trace32 version:

t32mamrm

As mentioned the patch adds an infinite loop. So we need to connect to MCU-R5F using the cmm script: j721e_evm_r5.cmm

After running the above CMM script.

Open the DCC window by running the following commands in the trace32 command window:

TERM.MODE String
TERM.METHOD DCC
TERM.SIZE 100. 1024.
TERM.SCROLL ON
TERM.view

The above should open a DCC Terminal

Now Set PC to immediate next instruction. As example in the below screenshot the infinite loop is at 0x41c00524 so Set the PC to 0x41c00526
to get out of while loop. Press run.

One should see DCC window with R5 SPL booting:

Now we are done with R5 SPL now close t32 and open 64 bit mode using t32marm64 and run a72 cmm script: j721e_evm_a72.cmm

Run commands mentioned above to open DCC window and then press run. You Should see a72 SPL & u-boot prints like below.
Press enter to get to u-boot command prompt.

The same should work for DRA820, DRA829 processors with just the changes in DTs and config files.

Best Regards,
Keerthy