Re: [PATCH 3/4] watchdog: sa11x0/pxa: get rid of get_clock_tick_rate

[Guenter Roeck]

On 09/19/2016 03:36 PM, Russell King - ARM Linux wrote:
> On Mon, Sep 19, 2016 at 01:08:16PM -0700, Guenter Roeck wrote:
> > On Mon, Sep 19, 2016 at 09:12:14PM +0200, Robert Jarzmik wrote:
> > > The OS timer rate used for the watchdog can now be fetched from the
> > > standard clock API. This will remove the last user of
> > > get_clock_tick_rate() in both pxa and sa11x0 architectures.
> > >
> > > Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
> >
> > Did you test this ? Potential problem, if built into the kernel, could be that
> > the clocks might not be ready by the time the driver is instantiated. Unless
> > this is converted to a platform driver, it won't be able to handle a
> > -EPROBE_DEFER from the clock subsystem.
>
> Really not a problem at all.  The OSTIMER0 is required for the system
> tick, and if that's not present, the kernel will be without any kind
> of time keeping, so a missing watchdog driver is the least of the
> problems.
>
> Therefore, both PXA and SA11x0 register their clocks really early to
> ensure that OSTIMER0 is available by the time_init() stage, which is
> way before driver probe time.

You are right. And, at least in qemu, it actually works.

Thanks,
Guenter