watchdog: it87_wdt: Work around non-working CIR interrupts

On some hardware platforms, the it87_wdt watchdog resets the machine
despite the watchdog daemon running and writing to /dev/watchdog.

This is due to Consumer IR buffer underrun interrupts being used as
triggers to reset the timer.  On some buggy hardware implementations
such as the iEi AFL-12A-N270 single-board computer, this method does
not work.

However, resetting the timer by writing its original timeout value in
its configuration register over and over again suppresses the unwanted
reboots.

Add a module option (nocir), 0 by default in order not to break existing
setups.  Setting it to 1 enables the workaround.

Fixes bug #42801 <https://bugzilla.kernel.org/show_bug.cgi?id=42801>.
Tested primarily on Linux 3.5.7, applies cleanly on Linux 3.13.5.

Signed-off-by: Marc van der Wal <x0r+kernel@x0r.fr>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 2 insertions, 0 deletions

diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt
index b39f35596ba2..692791cc674c 100644
--- a/Documentation/watchdog/watchdog-parameters.txt
+++ b/Documentation/watchdog/watchdog-parameters.txt
@@ -150,6 +150,8 @@ nowayout: Disable watchdog shutdown on close
 -------------------------------------------------
 it87_wdt:
 nogameport: Forbid the activation of game port, default=0
+nocir: Forbid the use of CIR (workaround for some buggy setups); set to 1 if
+system resets despite watchdog daemon running, default=0
 exclusive: Watchdog exclusive device open, default=1
 timeout: Watchdog timeout in seconds, default=60
 testmode: Watchdog test mode (1 = no reboot), default=0