[U-Boot-Users] watchdog support

[Wolfgang Denk]

In message <200401091148.40211.josef.baumgartner at telex.de> you wrote:
> 
> I'd like to have the possibility to configure u-boot for watchdog support but 
> disable the watchdog if there's no autoboot and I want to use the booter.
> I looked at the code but I found no such feature at the moment, am I right?

This is correct, because IMHO it makes  no  sense.  With  any  decent
watchdog  there  is no way by software to disable it once you started
it. I know that some devices allw  that,  but  there  is  no  general
solution.  For  example,  on  the  MPC8xx  family  of  processors the
relevant control register is  write-once,  i.  e.  once  written  you
cannot  overwrite  the  value  so  there  is no way to stop a running
watchdog. On some external watchdogs the behaviour is the same:  once
started, there is no way to stop them by software (only by reset).

> All solutions assume that an enabled watchdog could be disabled again which
> is not true for all watchdog implementations. I plan to use it on the Motorola
> MCF5272, there it is no problem.
> 
> What is your opinion and experience to this topic?

You can do it, if you like. I don't consider such a feature useful. A
watchdog, if present, is made for running, not for being stopped ;-)

Best regards,

Wolfgang Denk

-- 
See us @ Embedded World, Nuremberg, Feb 17 - 19,  Hall 12.0 Booth 440
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
How come everyone's going so slow if it's called rush hour?