Re: [PATCH 2/2] at91sam9_wdt: Allow watchdog to reset device at early boot

[Guenter Roeck <linux@roeck-us.net>]

On Mon, Feb 23, 2015 at 11:11:38AM +0200, Timo Kokkonen wrote:
[ ... ]

> 
> After all, we do have already watchdog_init_timeout function that parses the
> watchdog timeout argument from either device tree or from command line. How
> about if we expanded that interface? Maybe have a more generic
> watchdog_init_parmas() or something that parses the generic watchdog
> arguments, either from command line, device tree or ACPI or something. The
> device driver could replace call from watchdog_init_timeout() to
> watchdog_init_params() once it is ready to support other generic parameters,
> such as early-timeout-sec. Then the watchdog driver could do the right thing
> about whether watchdog should be left running or stopped and how long time
> should be given.
> 
Good idea.

> Alternatively, we could also let the watchdog core know a little more about
> the actual watchdog hardware, such as whether the HW is stoppable, whether
> it needs manual pinging by the kernel until user space has taken over. Or

Yes, all that will be needed. But, still, the stop-gap is that we'll need to
get buyin from the DT folks for the necessary properties. I have had the
outline for the necessary watchdog core implementation in my mind for a long
time, but I just don't have the time (nor the patience, quite frankly)
to get DT buyin.

> maybe we can just extend the timeout values until the user space has first
> opened it and then shorten the timeout automatically so that it doesn't take
> that long for the device to reset after a crash. Or some other behaviour
> that is common to many users. Suggestions are welcome.
> 
> Anyway, that is something that needs to be done to make watchdog core take
> more control over more of the generic watchdog behaviour. It just needs to
> be done so that we don't need to convert all drivers at once.
> 
Correct. It should not be that difficult do do that if designed properly.

Guenter