[U-Boot-Users] watchdog usage in U-Boot

[w.wegner at astro-kom.de]

Hi,

maybe this is again a stupid question, but I did not yet figure out
about it myself, so maybe somebody could give me some pointers
and/or correct my assumptions.

I want to use the watchdog in my MCF5373L board (which is
supported by U-Boot using the MCF532x code). I find
watchdog_init and so on but I did not see any of these being
called anywhere from within U-Boot. However, when enabling
the watchdog with CONFIG_WATCHDOG, the timer already
starts and will expire if any U-Boot internal task takes too long.

>From other posts I found some things that I would like to state
as assumptions, please correct me if any of these is wrong

- watchdog is not initialized by default, has to be done by
  board-specific code
- watchdog servicing (reset the counter) is also not done
  by default - has to be done by board-specific code
- I saw a patch by Wolfgang that splits udelay, but did not
  see how the watchdog_reset is handled by this? Where
  is this done?

My problem with this is:
- enabling watchdog with CONFIG_WATCHDOG will not
  disable the (normally enabled) watchdog during startup
  and thus it will time out with time-consuming tasks
  (like bootdelay or loading a large FPGA)
- I have no defined "watchdog service" before control is
  handed over to the linux kernel, so even when the linux
  kernel would have support for the correct watchdog (which
  I still have to implement), the timeout is never well defined
  at this point.

I can implement watchdog_init() in my board-specific startup
code and call watchdog_reset from time to time during my
board-specific FPGA loader, but first this seems not to be
a very elegant way and second this does not solve the problem
of bootdelay and handing over control to the linux kernel.

I would be happy if anybody could give some hints despite
this long text...

Regards,
Wolfgang