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SubjectRe: [PATCH v2 06/11] watchdog/hpwdt: Modify to use watchdog core.
On Tue, Feb 13, 2018 at 01:55:49PM -0800, Guenter Roeck wrote:
> On Tue, Feb 13, 2018 at 02:36:48PM -0700, Jerry Hoemann wrote:
> >
> >
> > >
> > > dev_dbg()
> >
> > I think you are proposing I do:
> >
> > dev_dbg(dev->parent, "settimeout = %d\n", val);
> >
> > This raises the issue that I didn't set parent and I believe I should have.
> >
> Correct.

Will fix.


> > > > retval = hpwdt_init_nmi_decoding(dev);
> > > > if (retval != 0)
> > > > goto error_init_nmi_decoding;
> > > >
> > > > - retval = misc_register(&hpwdt_miscdev);
> > > > + retval = watchdog_register_device(&hpwdt_dev);
> > > > if (retval < 0) {
> > > > - dev_warn(&dev->dev,
> > > > - "Unable to register miscdev on minor=%d (err=%d).\n",
> > > > - WATCHDOG_MINOR, retval);
> > > > - goto error_misc_register;
> > > > + dev_warn(&dev->dev, "Unable to register hpe watchdog (err=%d).\n", retval);
> > > > + goto error_wd_register;
> > > > + }
> > > > +
> > > > + watchdog_set_nowayout(&hpwdt_dev, nowayout);
> > > > + if (watchdog_init_timeout(&hpwdt_dev, soft_margin, NULL)) {
> > > > + dev_warn(&dev->dev, "Invalid soft_margin: %d. Using default\n", soft_margin);
> > > > + soft_margin = DEFAULT_MARGIN;
> > > > }
> > >
> > > In this case watchdog_init_timout() will:
> > > 1) Check if soft_margin is valid
> > > 2) if not, keep hpwdt_dev.timout intact (which is already set in
> > > declaration of hpwdt_dev)
> > >
> > > So we could remove the condition and only keep
> > > watchdog_init_timeout(&hpwdt_dev, soft_margin, NULL);
> > >
> > >
> > > Also, we need to set an invalid initial value for soft_margin to make
> > > the logic for watchdog_init_timeout work.
> > >
> > > i.e
> > > - static unsigned int soft_margin = DEFAULT_MARGIN; /* in seconds */
> > > + static unsigned int soft_margin;
> >
> >
> > I don't see the core printing a warning message if an invalid value
> > is specified for soft_margin when loading the module.
> >
> > I don't mind the hpwdt module correcting an out of range parameter, but I
> > don't think it should do so siliently.
> >
>
> The point here is that setting soft_margin to 0 and setting the
> timeout in the watchdog_device structure to DEFAULT_MARGIN
> means that it is not necessary to override it on error.

Yes, I don't need to set soft_margin = DEFAULT_MARGIN inside the
conditional on watchdog_init_timeout. I was doing that to keep
the value of soft_margin consistent with the value of hpwdt_dev.timeout
so that it would show the current timeout value in sysfs. But, as
you pointed out, the watchdog sysfs displays timeout. So, i don't
need that asignment anymore.

But, I want to keep the initialization:
static unsigned int soft_margin = DEFAULT_MARGIN;


Reasoning: I want soft_margin to be an optional parameter that
defaults to DEFAULT_MARGIN without warning. If soft_margin is initialized
to a value outside of the valid range, say N, the code can't tell the
difference between the static value of N or if the module was loaded with the
soft_margin=N. I only want to warn on the latter.


> If you want to be verbose, you can still log a warning message
> if the timeout provided by the module parameter is wrong.
>
> Anyway, this driver will presumably never support devicetree,
> so the watchdog core will never read the timeout from there,
> and this is not a showstopper.
>



--

-----------------------------------------------------------------------------
Jerry Hoemann Software Engineer Hewlett Packard Enterprise
-----------------------------------------------------------------------------

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