From: Richard Cochran <richardcochran@gmail.com>
To: Olivier Dautricourt <olivier.dautricourt@orolia.com>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>,
Alexandre Torgue <alexandre.torgue@st.com>,
Jose Abreu <joabreu@synopsys.com>,
"David S . Miller" <davem@davemloft.net>,
netdev@vger.kernel.org
Subject: Re: [PATCH 0/3] Patch series for a PTP Grandmaster use case using stmmac/gmac3 ptp clock
Date: Thu, 14 May 2020 17:37:06 -0700 [thread overview]
Message-ID: <20200515003706.GB18192@localhost> (raw)
In-Reply-To: <20200514150900.GA12924@orolia.com>
On Thu, May 14, 2020 at 05:09:01PM +0200, Olivier Dautricourt wrote:
> My issue is that the default behavior of the stmmac driver is to
> set the mac into fine mode which implies to continuously do frequency
> adjustment, So if i'm not mistaken using the nullf servo will not address
> that issue even if we are not doing explicit clock_adjtime syscalls.
Why not use the external time stamps from your GPS to do one of the
following?
A) Feed them into a user space PI controller and do frequency
correction, or
B) Feed the offsets into the hardware PLL (if that is present) using
the new PHC ADJ_OFFSET support (found in net-next).
I don't see a need for changing any kernel interfaces at all. If you
think there is such a need, then you will have to make some kind of
argument or justification for it.
BTW, support for B has been implemented in linuxptp, and the patches
will appear soon. We can also add it into the ts2phc program if you
like.
Thanks,
Richard
next prev parent reply other threads:[~2020-05-15 0:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-14 10:28 [PATCH 0/3] Patch series for a PTP Grandmaster use case using stmmac/gmac3 ptp clock Olivier Dautricourt
2020-05-14 10:28 ` [PATCH 1/3] net: stmmac: gmac3: add auxiliary snapshot support Olivier Dautricourt
2020-05-14 10:28 ` [PATCH 2/3] net: uapi: Add HWTSTAMP_FLAGS_ADJ_FINE/ADJ_COARSE Olivier Dautricourt
2020-05-14 13:38 ` Richard Cochran
2020-05-14 15:20 ` Olivier Dautricourt
2020-05-15 0:29 ` Richard Cochran
2020-05-14 10:28 ` [PATCH 3/3] net: stmmac: Support coarse mode through ioctl Olivier Dautricourt
2020-05-27 3:55 ` Richard Cochran
2020-06-03 16:12 ` Olivier Dautricourt
2020-05-14 13:53 ` [PATCH 0/3] Patch series for a PTP Grandmaster use case using stmmac/gmac3 ptp clock Richard Cochran
2020-05-14 15:09 ` Olivier Dautricourt
2020-05-15 0:37 ` Richard Cochran [this message]
2020-05-15 13:26 ` Julien Beraud
2020-05-15 23:30 ` Richard Cochran
2020-05-25 10:00 ` Olivier Dautricourt
2020-05-27 4:05 ` Richard Cochran
2020-06-03 15:17 ` Olivier Dautricourt
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