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authorPaolo Bonzini <pbonzini@redhat.com>2017-04-05 13:41:15 +0200
committerWim Van Sebroeck <wim@iguana.be>2017-05-19 10:42:11 +0200
commit1fccb73011ea8a5fa0c6d357c33fa29c695139ea (patch)
tree4cbf80c4de062175b1835036a5c303022a9ec6be /Documentation/watchdog
parent455a9a60b6d4afb293b0e63ec75cc8e82912a767 (diff)
downloadlinux-1fccb73011ea8a5fa0c6d357c33fa29c695139ea.tar.bz2
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 <andy.shevchenko@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Diffstat (limited to 'Documentation/watchdog')
-rw-r--r--Documentation/watchdog/watchdog-parameters.txt2
1 files changed, 1 insertions, 1 deletions
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<heartbeat<39 (TCO v1) or 613 (TCO v2), default=30)
+ (5<=heartbeat<=74 (TCO v1) or 1226 (TCO v2), default=30)
nowayout: Watchdog cannot be stopped once started
(default=kernel config parameter)
-------------------------------------------------