LX2 honeycomb requires serial connection to boot, linux reboot fails

We have two LX2 honeycombs with 32 GB DDR2 3200 and 1 TB NVME M.2 in an NZXT case. I put the image lx2160acex7_2000_700_3200_8_5_2-bc46e34.img.xz on the micro-SD card and followed the instructions from " HoneyComb / ClearFog CX Installation and Tips" to flash the NVME M.2.

We are seeing two things on both LX2s:

  1. Both require a serial connection to boot. Is this a configuration options somewhere?
  2. Linux boots fine. The problem is when I issue a “reboot” from the Linux command line. The board fails to boot back into Linux (see output below). From a cold boot, the board boots fine.

[ OK ] Reached target Reboot.
[ 235.273970] watchdog: watchdog0: watchdog did not stop!
[ 236.371243] reboot: Restarting system
NOTICE: BL2: v1.5(release):LSDK-20.12-8-g9115785
NOTICE: BL2: Built : 19:24:37, Jun 15 2021
ERROR: Read error = fffffffd
ERROR: Failed to load 29 firmware.
ERROR: Loading firmware failed (error code -2)
ERROR: Calculating DDR PHY registers failed.
PHY handshake timeout, ddr_dsr2 = 0
PHY handshake timeout, ddr_dsr2 = 0

NOTICE: 32 GB DDR4, 64-bit, CL=20, ECC off, 256B, CS0+CS1
ERROR: Read error = 1
ERROR: BL2: Failed to load image (-2)
Authentication failure

This looks like the uSDHC card is failing to reset properly on reboot. Can you try putting the firmware on a different uSDHC card?

I used a different uSDHC card and the linux “reboot” command works fine now. We purchased 2 of the following uSDHCs: SANDISK EDGE 16GB MICROSD CARD - A1 U1 CLASS 10 - BLANK. Neither work. Do you know why this would be?

All though there are not many cards with this issue, we have found a few in our 10 years as a company just do not work well when used to boot firmware from them. Every SDHC card has its own microcontroller inside that manages the nand and has an OS. A few cards had issues resetting fast enough when doing a normal reboot and then loading the firmware from the card…for instance if the power pin is not held off long enough the card would crash on reboot’s because the firmware got stuck in an in between state.

Of course this issue can be mitigated by moving the firmware to the spi-nor flash or eMMC and using that as your firmware boot device.

Thanks for the information. One more question - is there configuration somewhere that is causing the board to require a serial connection to boot?

No, there is no requirement or setting that would require a serial connection to boot.