AM4378: U-Boot Hang

Will you check u-boot bring-up tips as outlined in the link below:

https://software-dl.ti.com/processor-sdk-linux/esd/docs/06_03_00_106/AM335X/linux/How_to_Guides/Board_Port/U-Boot.html#u-boot-bringup-debugging-tips

So I am trying to debug uboot / SPL through CCS, and I can get to the point where I load the SPL memory and symbols. But when I try to run the code or just run a single instruction, the program counter jumps to address 0x9FF5000C and gets stuck and doesn't do anything. When I just try to boot normally and not run it through CCS I'm obviously getting past the SPL so I am very confused about what is going on.

I'd recommend using JTAG debugger to load SPL/u-boot symbols only, but not SPL/u-boot code which should be loaded normally.

It will also be helpful to add a spin loop in your SPL code which would facilitate JTAG debugger "attach" to running SPL code.

Upon successful JTAG attach, you can break the added "spin" loop to continue debugging your SPL/u-boot code. 

Okay, so after I get out of the spin loop, how do I set a breakpoint in U-boot so that I can step through the U-boot code and see where things go wrong?

Or more specifically, what offset do I need to enter when loading the U-Boot symbols in order to account for the relocation?

Hi Tanner, 

Yes, additional steps are indeed needed to account for u-boot relocation when JTAG debugging u-boot.

I wrote a note to show case on how to get the run-time u-boot relocation offset, and apply the offset to relocate the u-boot symbols.

I used T32 JTAG debugger in the example, and the flow would apply to any JTAG debugger.

Best,

-Hong

u-boot_JTAG_debug.pdf

Okay so I was able to get the U-boot symbols loaded and I can now debug the U-boot code. It looks like things are failing in the function mmc_probe() in mmc.c. From what I can tell, it seems like the line                        ret = device_probe(dev); is what causes it to crash.

I figured out the issue. I saw the note in the EVM dts file: "disable MMC3 as SDIO is not supported in U-Boot" - apparently this must have changed in one of the newer versions of U-Boot. After disabling mmc3 in the U-Boot DTS file, U-Boot now runs successfully.