When the watchdog device is not open by userspace, the kernel takes care of pinging it. When the open_timeout feature is in use, we should ensure that the hardware fires close to open_timeout ms after the kernel has assumed responsibility for the device (either at boot, or after userspace has had it open and magic-closed it). To do this, simply reuse the logic that is already in place for ensuring the same thing when userspace is responsible for regularly pinging the device: - When watchdog_active(wdd), this patch doesn't change anything. - When !watchdoc_active(wdd), the "virtual timeout" should be taken to be ->open_deadline". When the open_timeout feature is not used (i.e., when open_timeout was 0 the last time watchdog_set_open_deadline was called), ->open_deadline is KTIME_MAX, and the arithmetic ends up returning keepalive_interval as we used to. This has been tested on a Wandboard with various combinations of open_timeout (including fractional-seconds settings) and timeout-sec properties for the on-board watchdog by booting with 'init=/bin/sh', timestamping the lines on the serial console, and comparing the timestamp of the 'imx2-wdt 20bc000.wdog: timeout nnn sec' line with the timestamp of the 'U-Boot SPL ...' line (which appears just after reset). Suggested-by: Guenter Roeck <linux@xxxxxxxxxxxx> Signed-off-by: Rasmus Villemoes <rasmus.villemoes@xxxxxxxxx> --- drivers/watchdog/watchdog_dev.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 804da5b2ce02..39dd2329cbea 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -133,14 +133,15 @@ static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd) ktime_t virt_timeout; unsigned int hw_heartbeat_ms; - virt_timeout = ktime_add(wd_data->last_keepalive, - ms_to_ktime(timeout_ms)); + if (watchdog_active(wdd)) + virt_timeout = ktime_add(wd_data->last_keepalive, + ms_to_ktime(timeout_ms)); + else + virt_timeout = wd_data->open_deadline; + hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms); keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2); - if (!watchdog_active(wdd)) - return keepalive_interval; - /* * To ensure that the watchdog times out wdd->timeout seconds * after the most recent ping from userspace, the last -- 2.20.1
