Hello, We (the development team at my current employer company) are having a specific case of hardware configuraton. Namely, the same GPIO pin is used for both watchdog keepalive signaling and status LED blinking. The thing is, there are multiple blinking frequency modes for this LED, each with its own meaning (i.e. system/firmware states), so there's a need for changing the frequency/period dynamically from userspace. Previously I've done the thing implementing the timer period configuration by updating a special sysfs file with new values in the gpio_wdt driver. However since recently (commit 03bca15 in the kernel Git repo) the timer has been swapped out with the keepalive callback thing, which, as far as I can tell, supports updating the timeout period via the WDIOC_SETTIMEOUT ioctl. However this ioctl is insufficient for our purposes, in the sense that its minimum resolution is 1 whole second, while we need a 100 millisecond granularity at the very most. I could also simply disable the gpio_wdt altogether and just use a LED trigger driven configuration, but I highly doubt this would be a wise thing, since the whole point of the watchdog is monitoring responsiveness of the userspace. Also I gather that controlling the GPIO entirely from a userspace process is rather undesirable, too, as it might lead to confusing latencies sometimes, for a start. I'd like to hear your opinions on the preferred way(s) of implementing this for our product hardware on the most recent kernels, which could be sent to upstream to secure further backwards compatibility. Sincerely, Ilyas
