Hi Uwe, On 01/26/2016 12:07 AM, Uwe Kleine-König wrote:
Hello Guenter, On Mon, Jan 25, 2016 at 06:53:11PM -0800, Guenter Roeck wrote:From: Guenter Roeck <linux@xxxxxxxxxxxx> Some watchdogs require a minimum time between heartbeats. Examples are the watchdogs in DA9062 and AT91SAM9x. Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> --- v7: Rebased to v4.5-rc1 v6: Rebased to v4.4-rc2 v5: Rebased to v4.4-rc1 Fixed typo in documentation. v4: Added patch --- Documentation/watchdog/watchdog-kernel-api.txt | 3 +++ drivers/watchdog/watchdog_dev.c | 15 +++++++++++++++ include/linux/watchdog.h | 3 +++ 3 files changed, 21 insertions(+) diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index 62d49d6a7ff5..2221fb4f2739 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -52,6 +52,7 @@ struct watchdog_device { unsigned int timeout; unsigned int min_timeout; unsigned int max_timeout; + unsigned int min_hw_heartbeat_ms; unsigned int max_hw_timeout_ms; struct notifier_block reboot_nb; struct notifier_block restart_nb; @@ -81,6 +82,8 @@ It contains following fields: * max_timeout: the watchdog timer's maximum timeout value (in seconds), as seen from userspace. If set, the maximum configurable value for 'timeout'. Not used if max_hw_timeout_ms is non-zero. +* min_hw_heartbeat_ms: Minimum time between heartbeats sent to the chip, + in milli-seconds. * max_hw_timeout_ms: Maximum hardware timeout, in milli-seconds. If set, the infrastructure will send heartbeats to the watchdog driver if 'timeout' is larger than max_hw_timeout_ms, unless WDOG_ACTIVE diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 1a8f3861fe92..ff03cbc8e081 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -64,6 +64,7 @@ struct watchdog_core_data { struct watchdog_device *wdd; struct mutex lock; unsigned long last_keepalive; + unsigned long last_hw_keepalive; struct delayed_work work; unsigned long status; /* Internal status bits */ #define _WDOG_DEV_OPEN 0 /* Opened ? */ @@ -138,8 +139,19 @@ static inline void watchdog_update_worker(struct watchdog_device *wdd, static int __watchdog_ping(struct watchdog_device *wdd) { + struct watchdog_core_data *wd_data = wdd->wd_data; + unsigned long earliest_keepalive = wd_data->last_hw_keepalive + + msecs_to_jiffies(wdd->min_hw_heartbeat_ms); int err; + if (time_is_after_jiffies(earliest_keepalive)) { + mod_delayed_work(watchdog_wq, &wd_data->work, + earliest_keepalive - jiffies); + return 0; + } + + wd_data->last_hw_keepalive = jiffies; +Do you need to undo this assignment when ping fails?
I thought about it, but decided against it. I concluded that it is better in this situation to only try again after the minimum delay between heartbeats. Thanks, Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
