On Fri, Oct 19, 2018 at 04:52:13PM +, Keller, Jacob E wrote:
> > This should significantly improve the accuracy of the synchronization,
> > reduce the uncertainty in the readings to less than a half or third,
> > and also reduce the jitter as there are fewer register reads sensitive
> > to the
On Mon, Oct 22, 2018 at 03:48:02PM -0700, Richard Cochran wrote:
> On Fri, Oct 19, 2018 at 11:51:37AM +0200, Miroslav Lichvar wrote:
> > The extra timestamp doesn't fit the API of the PTP_SYS_OFFSET ioctl,
> > so it would need to shift the timestamp it returns by the missing
> > intervals (assuming
On Fri, Oct 19, 2018 at 04:52:13PM +, Keller, Jacob E wrote:
> Nice! I think this is good. I'd love to see some data to back it up, but it
> makes sense to me.
+1
On Fri, Oct 19, 2018 at 11:51:37AM +0200, Miroslav Lichvar wrote:
> A solution to this would be a new driver function that wraps the
> latching register read with readings of the system clock and return
> three timestamps instead of one. For example:
>
> ktime_get_real_ts64(&sys_ts1);
>
> -Original Message-
> From: netdev-ow...@vger.kernel.org [mailto:netdev-ow...@vger.kernel.org] On
> Behalf Of Miroslav Lichvar
> Sent: Friday, October 19, 2018 2:52 AM
> To: netdev@vger.kernel.org
> Cc: Richard Cochran ; Keller, Jacob E
>
> Subject: Improving
I think there might be a way how we could significantly improve
accuracy of synchronization between the system clock and a PTP
hardware clock, at least with some network drivers.
Currently, the PTP_SYS_OFFSET ioctl reads the system clock, reads the
PHC using the gettime64 function of the driver, a
