I’m investigating a BBB unit that got stuck during power-up. Only power led, and no data through console.
Rebooting or powering from USB or plug didn’t help.
It was recovered after re-flashing the eMMC
fdisk and write-tests on the MMC shown no failures.
After thousand of powr cycle tests, I managed to repeat a “weird” situation once again. Booting from SD, the MMC appears not properly configured. I can mount the MMC, but it is empty. I don’t know what caused that issue. I’ve been re-flashing the unit many times, and suddenly, it noticed the issue.
I only managed to recover the unit after re-flashing again. Rebboting/cycling the power didn’t worked. The environment is noise free, and power supply is stable
I got the MMC registers (/sys/kernel/debug/mmc1) during the fail scenario:
Working scenario:
clock: 52000000 Hz
vdd: 7 (1.65 - 1.95 V)
bus mode: 2 (push-pull)
chip select: 0 (don’t care)
power mode: 2 (on)
bus width: 3 (8 bits)
timing spec: 1 (mmc high-speed)
signal voltage: 0 (3.30 V)
regs:
CON: 0x00000620
HCTL: 0x00000b04
Failing scenario:
clock: 52000000 Hz
vdd: 21 (3.3 ~ 3.4 V)
bus mode: 2 (push-pull)
chip select: 0 (don’t care)
power mode: 2 (on)
bus width: 3 (8 bits)
timing spec: 1 (mmc high-speed)
signal voltage: 0 (3.30 V)
regs:
CON: 0x00008620
HCTL: 0x00000d00
It is suposed that u-boot/kernel setup the MMC host based on MMC data durind start-up. So I guess this kind of failure is hardware related.
Any ideas?
Thanks!