From: Miroslav Lichvar <mlichvar@redhat.com>
To: Richard Cochran <richardcochran@gmail.com>
Cc: netdev@vger.kernel.org, David Miller <davem@davemloft.net>,
Jacob Keller <jacob.e.keller@intel.com>,
John Stultz <john.stultz@linaro.org>
Subject: Re: [PATCH RFC net-next 1/1] ptp: add an ioctl to compare PHC time with system time
Date: Fri, 28 Sep 2012 10:50:31 +0200 [thread overview]
Message-ID: <20120928085031.GC29438@localhost> (raw)
In-Reply-To: <20120928082638.GB17636@netboy.at.omicron.at>
On Fri, Sep 28, 2012 at 10:26:38AM +0200, Richard Cochran wrote:
> I am guessing it would be possible to synchronize two PHC devices to
> within a few microseconds this way. Probably that is not good enough
> to implement a boundary clock, for example, so I have my doubts about
> the utility of this.
I think with two identical PHCs the error would be much smaller, even
if the two fastest consecutive readings took together ~5 microseconds.
The error could be measured with a short cable connecting the two ports
and compared the TX and RX timestamps, and compensated in the
software if it's significant.
> But in any case, it is possible, and I think that
> feature can wait for now.
Ok, thanks.
--
Miroslav Lichvar
next prev parent reply other threads:[~2012-09-28 8:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-27 18:12 [PATCH RFC net-next 0/1] ptp: add pseudo pps ioctl Richard Cochran
2012-09-27 18:12 ` [PATCH RFC net-next 1/1] ptp: add an ioctl to compare PHC time with system time Richard Cochran
2012-09-28 7:53 ` Miroslav Lichvar
2012-09-28 8:26 ` Richard Cochran
2012-09-28 8:50 ` Miroslav Lichvar [this message]
2012-10-01 22:33 ` Keller, Jacob E
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