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| author | Tero Kristo <t-kristo@ti.com> | 2020-07-17 16:29:56 +0300 |
|---|---|---|
| committer | Wim Van Sebroeck <wim@linux-watchdog.org> | 2020-08-05 18:43:02 +0200 |
| commit | cef9572e9af373cefd1adc9e771e89670da5da3c (patch) | |
| tree | f80b4b40eea485aa70c4d6cf400be986dafa92af /Documentation/watchdog | |
| parent | fbbe35dfcf949f4d6cf987648e52a85fc0c2a23a (diff) | |
| download | lwn-cef9572e9af373cefd1adc9e771e89670da5da3c.tar.gz lwn-cef9572e9af373cefd1adc9e771e89670da5da3c.zip | |
watchdog: add support for adjusting last known HW keepalive time
Certain watchdogs require the watchdog only to be pinged within a
specific time window, pinging too early or too late cause the watchdog
to fire. In cases where this sort of watchdog has been started before
kernel comes up, we must adjust the watchdog keepalive window to match
the actually running timer, so add a new driver API for this purpose.
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200717132958.14304-3-t-kristo@ti.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Diffstat (limited to 'Documentation/watchdog')
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.rst b/Documentation/watchdog/watchdog-kernel-api.rst index 068a55ee0d4a..baf44e986b07 100644 --- a/Documentation/watchdog/watchdog-kernel-api.rst +++ b/Documentation/watchdog/watchdog-kernel-api.rst @@ -336,3 +336,15 @@ an action is taken by a preconfigured pretimeout governor preassigned to the watchdog device. If watchdog pretimeout governor framework is not enabled, watchdog_notify_pretimeout() prints a notification message to the kernel log buffer. + +To set the last known HW keepalive time for a watchdog, the following function +should be used:: + + int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd, + unsigned int last_ping_ms) + +This function must be called immediately after watchdog registration. It +sets the last known hardware heartbeat to have happened last_ping_ms before +current time. Calling this is only needed if the watchdog is already running +when probe is called, and the watchdog can only be pinged after the +min_hw_heartbeat_ms time has passed from the last ping. |