Watchdog reset trigger for eMMC

[Anand Moon]

Hi All,

Using microSD card when I try to write into /dev/watchdog device
it triggers reboot of the board after timer expires.
-----------------------------------------------------------------------------------------------
root@odroidxu4l:~# echo 3 > /dev/watchdog
[ 1659.021844] watchdog: watchdog0: watchdog did not stop!
root@odroidxu4l:~#
root@odroidxu4l:~#
root@odroidxu4l:~#
root@odroidxu4l:~#
root@odroidxu4l:~#

U-Boot 2016.03-00665-g563d8d9-dirty (Apr 04 2016 - 22:27:07 +0930) for
ODROID-XU
3

CPU: Exynos5422 @ 800 MHz
Model: Odroid XU3 based on EXYNOS5422
Board: Odroid XU3 based on EXYNOS5422
Type: xu4
DRAM: 2 GiB
-----------------------------------------------------------------------------------------------
But when I try this on eMMC it just freezes.
I know we have to set and unset gpio pin (SD_0.RST) to trigger reset
before reboot.
-----------------------------------------------------------------------------------------------
root@odroidxu4e:~# echo 4 > /dev/watchdog
[ 639.192617] [c3] watchdog watchdog0: watchdog did not stop!
root@odroidxu4e:~#
root@odroidxu4e:~#
root@odroidxu4e:~#
-----------------------------------------------------------------------------------------------
I would like to know what is way board reset after watchdog reset after timeout.

Best Regards
-Anand Moon

[Marek Szyprowski]

Hi Anand

In my opinion hw watchdog reset is non-functional on Odroid U3/XU3/XU4
boards due to
hardware design (eMMC reset line triggered from software). I see no way
to workaround
this issue in the software.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

[Anand Moon]

Hi Marek

Yes It's difficult to reset eMMC card.
Thanks for clarification.

Best Regards
-Anand Moon