SOM board fails to boot with custom carrrier board

[skyfall0119]

Description

I have SOM board with custom carrier board, which is designed pretty much the same with the one for dev base board except unnecessary parts (bluetooth, ethernet port, HDMI, audio port, etc.
one board I tried to follow the SOM get started guide.

https://coral.ai/docs/som/get-started/#next-steps
using ubuntu 24.04.1, installed fastboot, and download & flash through USB.
terminal says its installed successfully and it will reboot. but the terminal prompt never got back to me.
i waited for about 15minutes and decided to manually reboot.

i connected uart to check whats going on, and found that during the boot it stopped at some point.

....
[ 2.555800] [drm] VCO frequency is 5940000
[ 2.559916] [drm] VCO frequency (5940000 KHz) is supported. Settings found in row 14

when I checked the dev board for comparison, it goes

[ 2.557749] [drm] VCO frequency is 5940000
[ 2.561920] [drm] VCO frequency (5940000 KHz) is supported. Settings found in row 14
------------------ SOM BOARD LOG END ---------------------
[ 2.593809] [drm] CDN_API_General_Write_Register_blocking LANES_CONFIG ret = 0
[ 2.601074] [drm] Failed to get HDCP config - using HDCP 2.2 only
[ 2.607275] [drm] Failed to initialize HDCP
.....

with some googling, CDN_API_General_Write_Register_blocking is related to HDMI.
link
maybe we didn't have HDMI on our board, it stopped there I guess?

what is the main reason for the boot failure? can you confirm that its because of the missing HDMI? if so, then how can we configure the board so we can boot without those unnecessary parts.

also, another board I just tried to flash the image with regular dev board procedure (with SD card) to see if it works.

on the log it says
Hit any key to stop autoboot: 0
** Unrecognized filesystem type **
Executing script at 40480000
Wrong image format for "source" command
Starting auxiliary core at 0x00000000 ...
u-boot =>

is there a way to reset the board? this board is no more detected with USB after the flashing.

EDIT :
I managed to flash again by resetting usb and initialize fastboot usb from the board.
and I was able to get the log from flashing again.

as you can see it stopped while booting.
left is the board terminal, and right is the host computer terminal where i ran a fastboot flash

Click to expand!

Issue Type

Build/Install

Operating System

Ubuntu

Coral Device

SoM

Other Devices

No response

Programming Language

No response

Relevant Log Output

********* SOM board booting log ***************
[    2.534995] [drm] Pixel clock frequency: 594000 KHz, character clock frequency: 594000, color depth is 8-bit.
[    2.544936] [drm] Pixel clock frequency (594000 KHz) is supported in this color depth (8-bit). Settings found in row 27
[    2.555800] [drm] VCO frequency is 5940000
[    2.559916] [drm] VCO frequency (5940000 KHz) is supported. Settings found in row 14



*********** coral dev board boot log ***************
....
[    2.557749] [drm] VCO frequency is 5940000
[    2.561920] [drm] VCO frequency (5940000 KHz) is supported. Settings found in row 14
[    2.593809] [drm] CDN_API_General_Write_Register_blocking LANES_CONFIG ret = 0
[    2.601074] [drm] Failed to get HDCP config - using HDCP 2.2 only
[    2.607275] [drm] Failed to initialize HDCP
....


***************** flashed with SD card **********
** Unrecognized filesystem type **
## Executing script at 40480000
Wrong image format for "source" command
## Starting auxiliary core at 0x00000000 ..
u-boot =>

[skyfall0119]

I found the way to disable.

https://www.reddit.com/r/kernel/comments/hznkem/uboot_hangs_while_booting_mendel_linux_on_custom/

since I had the dev board, I swapped the original SOM board on the dev board with my som board.
this allows the boot.

once Im in, I followed the instruction to disable the HDMI
https://gist.github.com/Namburger/f700eb6b18bd1e3697638088d5995c8b

moved SOM board back to custom board, and it boots just fine.

still, I'm not sure how I could have configured it without the working baseboard. it has to boot successfully in order to modify the device tree..

[google-coral-bot]

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