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

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Wed, 18 Feb 2015 09:50:02 -0800
Guenter Roeck <linux@roeck-us.net> wrote:

> On Wed, Feb 18, 2015 at 05:00:33PM +0100, Alexandre Belloni wrote:
> > Hi,
> > 
> > On 18/02/2015 at 06:50:44 -0800, Guenter Roeck wrote :
> > > >>>   Optional properties:
> > > >>>   - timeout-sec: Contains the watchdog timeout in seconds.
> > > >>>+- early-timeout-sec: If present, specifies a timeout value in seconds
> > > >>>+  that the driver keeps on ticking the watchdog HW on behalf of user
> > > >>>+  space. Once this timeout expires watchdog is left to expire in
> > > >>>+  timeout-sec seconds. If this propery is set to zero, watchdog is
> > > >>>+  started (or left running) so that a reset occurs in timeout-sec
> > > >>>+  since the watchdog was started.
> > > >>>
> > > >>>   Example:
> > > >>>
> > > >>>   watchdog {
> > > >>>   	 timeout-sec = <60>;
> > > >>>+	 early-timeout-sec = <120>;
> > > >>
> > > >>That is not a generic property as you defined it; if so,
> > > >>it would have to be implemented in the watchdog core code,
> > > >>not in the at91 code. You'll have to document it in the bindings
> > > >>description for at91sam9_wdt.
> > > >
> > > >Then, if this is a controller specific property, it should be defined
> > > >with the 'atmel,' prefix.
> > > >We're kind of looping here: the initial discussion was "is there a need
> > > >for this property to be a generic one ?", and now you're saying no,
> > > >while you previously left the door opened.
> > > >
> > > >Tomi is proposing a generic approach, as you asked him to. I agree that
> > > >parsing the property in core code and making its value part of the
> > > >generic watchdog struct makes sense (that's what I proposed to Tomi a
> > > >few weeks ago).
> > > >
> > > Hmm ... the problem here is that the property description creates the
> > > assumption or expectation that the property is used if defined,
> > > which is not the case.
> > > 
> > > I am not sure how to best resolve this. Maybe a comment in the property
> > > description stating that implementation of is device (driver) dependent ?
> > > After all, that is true for the timeout-sec property as well.
> > > 
> > 
> > I would leave it in the generic file and state that it may not be
> > implemented in the driver. That way, the property is documented for new
> > driver writers.
> > 
> Yes, that would be fine ok me.

Great!
Timo can you change the documentation accordingly ?


-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com