Re: How to ensure clock is updated in a device driver

[Jerry Stuckle <jstuckle@attglobal.net>]

On 5/13/2014 2:58 AM, Andrei POPESCU wrote:
> On Lu, 12 mai 14, 16:58:21, Jerry Stuckle wrote:
> > Hi, all,
> >
> > I'm working on a driver to monitor a device.  One of the things I need is an
> > accurate time, and ARM clocks are notoriously subject to drift. Once the
> > system is booted, that's not a problem as I can use an ntp server in a cron
> > job to correct the time as necessary.
> >
> > However, I need the time to be accurate during device driver initialization,
> > also.  How can I ensure ntp has run to update the system clock during
> > initialization?
>
> This is probably an obvious solution, but I'll post it anyway: you could
> (re)load your driver in an initscript that depends on ntp.
>
> Kind regards,
> Andrei

Andrei,

It would be a good solution in many instances, but once everything is 
working correctly we plan to build everything into a custom kernel.  So 
I need a way to determine when the clock has been updated (or failed, 
i.e. due to lack of connectivity).  I was hoping there was a way to 
determine that.

But thanks for the suggestion; if we were loading the driver separately 
it would be a great idea.  But even now it's still useful; I guess I 
could issue an IOCTL call to do the initialization in the initscript.

Jerry