Imx7d unwanted reset in uboot after reset

Technical Support
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1

Hi,
we have seen this:

  • application running which uses watchdog (/dev/watchdog)
  • external reset [nRESET_EXT]
  • booting starts
  • stop autoboot (hit a key)
  • unwanted reset

I also added the output of the booting sequence.

how can we avoid this behaviour? we guess that the watchdog in PMIC doesn’t stop?
Many thanks in advance!
Betty

link text

2

hi @Betty

Could your provide the Software Version ( uname -a )of your module? Which carrier board are your using?
What is your application?

We are not aware of an issue of unwanted reset when the module is stoppped in uboot. Does this reset happens always or randomly?

Best regards, Jaski

3

Hi @jaski.tx

We have a customized system. We do not use a carrier board, we have our own hardware.
Kernel version is 4.9.76.0000 and we adapted uboot 2016.11.

It happens always, if the watchdog was running.

If you don’t see this behaviour with toradex software, do you somehow reset PMIC in uboot? Is there maybe something which we had overseen when adapting uboot? Do you know how to reset/disable PMIC watchdog out of uboot?

Many thanks in advance

Betty

4

So you have your own custom carrier board.
When the watchdog is active, its normal that it will do a reset.

In our regular images, the watchdog is not active, you have to trigger it to make it active.
And if there is an external reset, the module gets reset and watchdog is not more active. So what did you change in UBoot exactly?

5

So you have your own custom carrier board.
When the watchdog is active, its normal that it will do a reset.
Yes.

In our regular images, the watchdog is not active, you have to trigger it to make it active.
And if there is an external reset, the module gets reset and watchdog is not more active.
That’s what I would expect. But somehow the watchdog is still running in our case.

So what did you change in UBoot exactly?
We did not change the partition but we overwrote “bootcmd” enviroment variable.

Many thanks

6

That’s what I would expect. But somehow the watchdog is still running in our case.

Thats strange. Did you try this with one of toradex carrier baords and/or with our regular bsp image?

We did not change the partition but we overwrote “bootcmd” enviroment variable.

What is this bootcmd variable in your case?

7

Sorry it took so long. Now I tested it on the colibri carrier board with a regular imgage and saw the same behaviour.

What I used:

  • Colibri Evaluation Board V3.2B
  • Colibri imx7d as described earlier
  • Colibri-iMX7_LXDE-Image_2.7 (downloaded it and put it on a colibri board with easy Installer)
  • C example from https://developer.toradex.com/knowledge-base/watchdog-(linux) to run the watchdog (adjusted timeout to 8s)
  • Pushed reset button after running example parogram
  • Hit any key after restart
  • waited about 8s
  • Reboot!
8

hi @Betty

Thanks for your Input. We could reproduce the Issue on our site. We will check internally for this Issue and come back soon to you.

Best regards, Jaski

10

Hi @jaski.tx thank you very much. Regards

11

hi @Betty

We checked internally and the issue is related to the Design of SOM.
So we wanted to know is this a blocker point for you?

12

Hi @jaski.tx
No this is not a blocker point for us. It’s just not very practical because we do ftp update out of uboot during developing. And it would be nice to have this somewhere stated to avoid that someone else is searching the cause of this behaviour like we did…

Anyway, thanks a lot for your help and patience and let me know when this gets fixed some day.

Regards Betty

13

hi @Betty
Thanks for your Input and work.
It’s true that is not nice. We will do further Investigation and come back soon to you .

Best regards,
Jaski