allow opting out of WATCHDOG_RESET() from timer interrupt
Having WATCHDOG_RESET() called automatically from the timer interrupt
runs counter to the idea of a watchdog device - if the board runs into
an infinite loops with interrupts still enabled, the watchdog will
never fire.
When using CONFIG_(SPL_)WDT, the watchdog_reset function is a lot more
complicated than just poking a few SOC-specific registers - it
involves accessing all kinds of global data, and if the interrupt
happens at the wrong time (say, in the middle of an WATCHDOG_RESET()
call from ordinary code), that can end up corrupting said global data.
Allow the board to opt out of calling WATCHDOG_RESET() from the timer
interrupt handler by setting CONFIG_SYS_WATCHDOG_FREQ to 0 - as that
setting is currently nonsensical (it would be compile-time
divide-by-zero), it cannot affect any existing boards.
Add documentation for both the existing and extended meaning of
CONFIG_SYS_WATCHDOG_FREQ.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
diff --git a/README b/README
index a565748..ad13092 100644
--- a/README
+++ b/README
@@ -747,6 +747,15 @@
SoC, then define this variable and provide board
specific code for the "hw_watchdog_reset" function.
+ CONFIG_SYS_WATCHDOG_FREQ
+ Some platforms automatically call WATCHDOG_RESET()
+ from the timer interrupt handler every
+ CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
+ board configuration file, a default of CONFIG_SYS_HZ/2
+ (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
+ to 0 disables calling WATCHDOG_RESET() from the timer
+ interrupt.
+
- Real-Time Clock:
When CONFIG_CMD_DATE is selected, the type of the RTC