Hang when power on/off imx6 many times

[tuyenpham]

Dear all,

1. I implement test case: on/off power imx6 1000 times and check it can booting in Linux kernel? I found that sometimes (rate ~20/1000 times) imx6 hang at: switch to ldo_bypass mode!. it can not booting in Linux kernel (as log below)

My questions 1: what is the root cause of this problem? anyone see this problem before?

2. When imx6 booting in Linux to run my application. Sometimes It hang when start some systemd service etc: bluetooth.service....

My questions 2: how about overcome hang when systemd start?

Attachment console booting in question 1.

thanks and regards,

## Booting kernel from Legacy Image at 12000000 ...
   Image Name:   Linux-3.10.17-g94bb090-dirty
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    6059768 Bytes = 5.8 MiB
   Load Address: 10008000
   Entry Point:  10008000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 18000000
   Booting using the fdt blob at 0x18000000
   Loading Kernel Image ... OK
OK
switch to ldo_bypass mode!

[igorpadykov]

Hi tuyen

please verify that all i.MX6 power supplies lines, connected to capacitors were fully discharged before next power on,

that is no voltages were left on them. Also power should be fully turned off from all board as it is done

on p.21 spf-27392 with signal PWRON.

Schematics (1)
i.MX6_SABRE_SDP_DESIGNFILES
http://www.nxp.com/products/software-and-tools/hardware-development-tools/sabre-development-system/s...

Best regards
igor
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[tuyenpham]

Hi igor,

Consider you're correct. The imx6 is not hang when I increase power off time to 30s. And I have another questions:

1. How to increase fully discharge time to overcome this hang?

2. Can I use WatchDog in uboot to solve it? The watchdog of imx6 can disable by software when we don't use it?

thanks and regards,

[tuyenpham]

Thanks igor,

Now, I power on/off flow period 10s off + 50s on. I'll change to 30s on + 30s of to make sure fully discharge on all capacitor and retry testing.

thanks so much,

tuyen