From 1fccb73011ea8a5fa0c6d357c33fa29c695139ea Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 5 Apr 2017 13:41:15 +0200 Subject: iTCO_wdt: all versions count down twice The ICH9 is listed as having TCO v2, and indeed the behavior in the datasheet corresponds to v2 (for example the NO_REBOOT flag is accessible via the 16KiB-aligned Root Complex Base Address). However, the TCO counts twice just like in v1; the documentation of the SECOND_TO_STS bit says: "ICH9 sets this bit to 1 to indicate that the TIMEOUT bit had been (or is currently) set and a second timeout occurred before the TCO_RLD register was written. If this bit is set and the NO_REBOOT config bit is 0, then the ICH9 will reboot the system after the second timeout. The same can be found in the BayTrail (Atom E3800) datasheet, and even HOWTOs around the Internet say that it will reboot after _twice_ the specified heartbeat. I did not find the Apollo Lake datasheet, but because v4/v5 has a SECOND_TO_STS bit just like the previous version I'm enabling this for Apollo Lake as well. Cc: linux-watchdog@vger.kernel.org Reviewed-by: Andy Shevchenko Signed-off-by: Paolo Bonzini Reviewed-by: Guenter Roeck Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- Documentation/watchdog/watchdog-parameters.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation/watchdog') diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt index 4f7d86dd0a5d..914518aeb972 100644 --- a/Documentation/watchdog/watchdog-parameters.txt +++ b/Documentation/watchdog/watchdog-parameters.txt @@ -117,7 +117,7 @@ nowayout: Watchdog cannot be stopped once started ------------------------------------------------- iTCO_wdt: heartbeat: Watchdog heartbeat in seconds. - (2