I need to use PTP synchronization for synchronizing video stream (something
like this). To do it I have to adjust the clock, but using the system clock
looks like bad architecture decision. So I decided to ask is it possible to
have some separate clock, that will be dedicated only for this purpose.
By the way, 802.1AS-2011 standard describes application interfaces (chapter
9), especially ClockTarget. Is it implemented in ptp4l, or it should be
implemented using some custom software?
On Thu, Mar 22, 2018 at 6:12 PM, Richard Cochran <richardcoch...@gmail.com>
wrote:
>
> On Thu, Mar 22, 2018 at 09:15:31AM +0200, Yan Yankovskyi via
> Linuxptp-users wrote:
> > In case of use software timestamping we are adjusting system clock. Is it
> > possible to create another clock, and use it in ptp4l? I see that in
> > clock_create function in case if phc_index < 0 we use CLOCK_REALTIME as
> > value for clkid, so I suppose it isn't possible.
>
> Right. The kernel delivers SW time stamps on CLOCK_REALTIME, and so
> the use of CLOCK_REALTIME with SW time stamping is hard coded.
>
> > But it implies that using
> > software timestamping we are limited to only one instance of ptp4l at the
> > same time, while using hardware timestamping we can launch as many ptp4l
> > instances simultaneously, as many physical devices we have, right?
>
> Well, using option free_running=1 you can have as many instances as
> you like, but I'm not sure why would anyone want to do this. You can
> even launch multiple ptp4l programs on the same interface in different
> PTP domains, assuming at most one instance has free_running=0.
>
> What problem are you trying to solve?
>
> Thanks,
> Richard
>
>
--
Best regards,
Yan Yankovskyi | Junior Software Engineer, Ukraine
GlobalLogic
M +380.95.049.64.73 <+380950496473> Skype huandesale
www.globallogic.com
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