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Soft reboot hangs on "Rebooting... reboot: Restarting system"

Hi,

I'm working on teh TS-7553-V2 (Rev. D), with the ts7553-V2-dec152017.tar.bz2 image.


I tried soft-rebooting the system with the reboot command.

System entered shut-down flow, but hanged in:

[  OK  ] Stopped Replay Read-Ahead Data.
         Stopping Collect Read-Ahead Data...
[  OK  ] Stopped Collect Read-Ahead Data.
[  OK  ] Reached target Shutdown.
[ 1680.164379] watchdog watchdog0: watchdog did not stop!
[ 1680.848623] reboot: Restarting system

 I've seen some stuff in the internet (including imx6 fixes).


Best Answer

In reviewing our forums I noticed this post did not update with the rest of Rami's story, which was concluded privately in his support ticket.


The problem, such as it were, turned out to be that his USB Cellular modem had some internal capacitors that held the power rails up while the power management chip was attempting to perform the reset function.


The solution in this case is to deliberately turn off USB power before issuing the reboot command.  This causes power to be physically cut from the USB ports, shielding the internal power rail from the external device's pull.


Further information on the USB Power enable signal is found here:

https://wiki.embeddedarm.com/wiki/TS-7553-V2#Special_DIO


Good afternoon Rami,


One of the other engineers here pointed out that it might be interesting to see some diagnostic output.  Could you run and post this for us?


tshwctl --info

uname -a

cat /root.version 


This might shed some light on the trouble you're describing.


Hi Rami,


Can you give us more detail?  I have a TS-7553-V2 Rev. D right here, running the December 15 image,  and it reboots consistently on command.


  1. <snip>
  2. [ OK ] Stopped Collect Read-Ahead Data. 
  3. [ OK ] Reached target Shutdown. 
  4. [ 28.403643] watchdog watchdog0: watchdog did not stop! 
  5. [ 30.694263] reboot: Restarting system 


  6. U-Boot 2016.03-00308-g9c14675 (Jan 15 2018 - 09:42:45 -0800) 

  7. CPU: Freescale i.MX6UL rev1.1 at 396 MHz 
  8. Reset cause: POR 
  9. Board: Technologic Systems TS-7553-V2 
  10. I2C: ready 
  11. DRAM: 512 MiB 
  12. MMC: FSL_SDHC: 0, FSL_SDHC: 1 
  13. *** Warning - bad CRC, using default environment 

  14. Net: FEC0 [PRIME] 
  15. Booting from the eMMC ... 
  16. ** File not found /boot/boot.ub ** 
  17. 34511 bytes read in 167 ms (201.2 KiB/s) 
  18. 5460520 bytes read in 391 ms (13.3 MiB/s) 
  19. NO CHRG jumper is set, not waiting 
  20. Kernel image @ 0x80800000 [ 0x000000 - 0x535228 ] 
  21. ## Flattened Device Tree blob at 83000000 
  22.    Booting using the fdt blob at 0x83000000 
  23.    Using Device Tree in place at 83000000, end 8300b6ce 

  24. Starting kernel ... 


  25. Welcome to Debian GNU/Linux 8 (jessie)! 
  26. </snip>



Answer

In reviewing our forums I noticed this post did not update with the rest of Rami's story, which was concluded privately in his support ticket.


The problem, such as it were, turned out to be that his USB Cellular modem had some internal capacitors that held the power rails up while the power management chip was attempting to perform the reset function.


The solution in this case is to deliberately turn off USB power before issuing the reboot command.  This causes power to be physically cut from the USB ports, shielding the internal power rail from the external device's pull.


Further information on the USB Power enable signal is found here:

https://wiki.embeddedarm.com/wiki/TS-7553-V2#Special_DIO

Usually reboot command succeeds.

I tried looking for a scenario to reproduce... not much luck.

Maybe something to do with the USB-cellular modem connected and LAN cable (only peripherals I'm using).

I happened maybe ~5 times out of ~50 attempts.

I haven't dove into it so much, hoped it's a known issue (or this-or-that miss-use on my side)

 

[root@ts-imx6ul: ~] > uname -a
Linux ts-imx6ul 4.1.15-g7aa498a #16 SMP PREEMPT Fri Dec 15 13:19:46 PST 2017 armv7l GNU/Linux
[root@ts-imx6ul: ~] > tshwctl --info
model=7553
boardopt=2
[root@ts-imx6ul: ~] > cat /root.version
2017-12-15

 

Sorry for the late replay.

I managed to constantly reproduce the 'hang', by connecting one of the cellular modems I'm using, Sierra Wireless GL6110.

It's an old modem we're still using, GPRS, full-speed, creating a /dev/ttyACM0 device.


A newer USB modem, Gemalto EHS6T, high-speed, creates /dev/ttyACM0 to /dev/ttyACM6, but reboots OK.


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