[LinuxPPS] http://lkml.org/lkml/2008/4/11/42

[Bernhard Schiffner]

Am Samstag, 19. April 2008 18:37 schrieb Rodolfo Giometti:
> On Fri, Apr 18, 2008 at 05:16:50PM +0200, Udo van den Heuvel wrote:
> > BTW: Besides the 'x86 lowlevel irq way' of obtaining timestamps (which
> > works well), could we just duplicate the serial code to some extent
> > and use that copy for the PPS stuff?
> > This driver could be as minimal as we like.
> >
> > (I doubt that idea will be accepted at the lkml...)
> >
> > So what options do we have?
> >
> > - Current approach
> > - Lowlevel x86-only irq method (works best for resolution)
> > - Copying the serial driver as I proposed above
> > - Alan's ldisc idea (how much does it differ?)
> > - ...
> >
> > Please comment.
>
> I think we could do like this:
>
> Step 1) Fix up the lowlevel x86-only irq method which improve
>         resolution so much.
>
> 	This step should be easy to implement regarding the timestamp
> 	issue, a bit complicated regarding the echo function...
>
> Step 2) We can completely remove the PPS code from tty serial code
> 	by using a "generic" client (maybe called pps-generic-irq?)
> 	which can be used with any IRQ source.
>
> 	We can implement something that loaded as follow:
>
> 	$ modprobe pps-generic-irq.ko irqs=1,4
>
> 	enables two PPS sources linked with IRQs 1 and 4.
>
> The first step should improve resolution and the second should remove
> the problem with serial code.
>
> What do you think about these solutions? :)
>
> Rodolfo