[U-Boot] [PATCH] at91: Don't initialize watchdog if CONFIG_SYS_WDTC_WDMR_VAL is undefined

[Wolfgang Denk]

Dear Alexander,

In message <201007220924.51614.alexander.stein at systec-electronic.com> you wrote:
> 
> > This is normal. Any watchdog that is worth the name will behave
> > similar.
> 
> Well, I encountered several watchdog which start only after the first trigger.

Me too. They are ok in many applications, but completely unacceptable
for advanced security requirements.

> Of course, if CONFIG_HW_WATCHDOG and CONFIG_AT91SAM9_WATCHDOG is set, u-boot 
> should use/trigger the watchdog. But (re-)programming the watchdog on AT91 is 
> not _always_ necessary. Without programming (using CONFIG_SYS_WDTC_WDMR_VAL), 
> the watchdog just runs with default settings, allowing e.g. Linux to reprogram 
> it later.
> This patch allows to program the watchdog from u-boot, if wanted, but also 
> allows to reprogram it later from Linux. While triggering the watchdog from u-
> boot itself does still work, wrt. the default watchdog settings.

I can see the intention, but this should not depend on "val" being
defined or not - and it needs explicit documentation (in the README,
for example).

Best regards,

Wolfgang Denk

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