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From: Richard Cochran <richardcochran@gmail.com>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Sergey Organov <sorganov@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Fugang Duan <fugang.duan@nxp.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	andrew@lunn.ch
Subject: Re: [PATCH  1/5] net: fec: properly support external PTP PHY for hardware time stamping
Date: Wed, 8 Jul 2020 04:00:53 -0700	[thread overview]
Message-ID: <20200708110053.GC9080@hoboy> (raw)
In-Reply-To: <20200707070437.gyfoulyezi6ubmdv@skbuf>

On Tue, Jul 07, 2020 at 10:04:37AM +0300, Vladimir Oltean wrote:
> > > We do it like this:
> > > - DSA: If there is a timestamping switch stacked on top of a
> > >   timestamping Ethernet MAC, the switch hijacks the .ndo_do_ioctl of the
> > >   host port, and you are supposed to use the PTP clock of the switch,
> > >   through the .ndo_do_ioctl of its own (virtual) net devices. This
> > >   approach works without changing any code in each individual Ethernet
> > >   MAC driver.
> > > - PHY: The Ethernet MAC driver needs to be kind enough to check whether
> > >   the PHY supports hw timestamping, and pass this ioctl to that PHY
> > >   while making sure it doesn't do anything stupid in the meanwhile, like
> > >   also acting upon that timestamping request itself.
> > >
> > > Both are finicky in their own ways. There is no real way for the user to
> > > select which PHC they want to use. The assumption is that you'd always
> > > want to use the outermost one, and that things in the kernel side always
> > > collaborate towards that end.

Vladimir, your explanations in this thread are valuable.  Please
consider converting them into a patch to expand

   Documentation/networking/timestamping.rst


Thanks,
Richard

  parent reply	other threads:[~2020-07-08 11:00 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-06 14:26 [PATCH 0/5] net: fec: fix external PTP PHY support Sergey Organov
2020-07-06 14:26 ` [PATCH 1/5] net: fec: properly support external PTP PHY for hardware time stamping Sergey Organov
2020-07-06 15:08   ` Vladimir Oltean
2020-07-06 15:21     ` Sergey Organov
2020-07-06 15:47       ` Vladimir Oltean
2020-07-06 18:33         ` Sergey Organov
2020-07-07  7:04           ` Vladimir Oltean
2020-07-07 15:29             ` Sergey Organov
2020-07-08 11:00             ` Richard Cochran [this message]
2020-07-08 10:55           ` Richard Cochran
2020-07-06 14:26 ` [PATCH 2/5] net: fec: enable to use PPS feature without " Sergey Organov
2020-07-07  4:05   ` [EXT] " Andy Duan
2020-07-07 14:29     ` Sergey Organov
2020-07-06 14:26 ` [PATCH 3/5] net: fec: initialize clock with 0 rather than current kernel time Sergey Organov
2020-07-06 15:27   ` Vladimir Oltean
2020-07-06 18:24     ` Sergey Organov
2020-07-07  6:36       ` Vladimir Oltean
2020-07-07 16:07         ` Sergey Organov
2020-07-07 16:43           ` Vladimir Oltean
2020-07-07 17:09             ` Sergey Organov
2020-07-07 17:12               ` Vladimir Oltean
2020-07-07 17:56                 ` Sergey Organov
2020-07-08 11:15                   ` Richard Cochran
2020-07-08 12:14                     ` Sergey Organov
2020-07-08 11:11             ` Richard Cochran
2020-07-08 11:04     ` Richard Cochran
2020-07-08 12:24       ` Sergey Organov
2020-07-08 12:37       ` Sergey Organov
2020-07-08 14:48         ` Richard Cochran
2020-07-08 17:18           ` Sergey Organov
2020-07-06 14:26 ` [PATCH 4/5] net: fec: get rid of redundant code in fec_ptp_set() Sergey Organov
2020-07-07  4:08   ` [EXT] " Andy Duan
2020-07-07 14:43     ` Sergey Organov
2020-07-08  5:34       ` Andy Duan
2020-07-08  8:48         ` Sergey Organov
2020-07-08  8:57           ` Andy Duan
2020-07-08 12:26             ` Sergey Organov
2020-07-06 14:26 ` [PATCH 5/5] net: fec: replace snprintf() with strlcpy() in fec_ptp_init() Sergey Organov
2020-07-11 12:08 ` [PATCH v2 net] net: fec: fix hardware time stamping by external devices Sergey Organov
2020-07-11 23:19   ` Vladimir Oltean
2020-07-12 14:16     ` Sergey Organov
2020-07-12 14:47       ` Andrew Lunn
2020-07-12 15:01       ` Vladimir Oltean
2020-07-12 17:29         ` Sergey Organov
2020-07-12 19:33           ` Vladimir Oltean
2020-07-12 22:32             ` Sergey Organov
2020-07-12 23:15               ` Vladimir Oltean
2020-07-14 12:39                 ` Sergey Organov
2020-07-14 14:23                   ` Vladimir Oltean
2020-07-14 14:35                     ` Sergey Organov
2020-07-14 14:44                     ` Vladimir Oltean
2020-07-14 16:18                       ` Sergey Organov
2020-07-14 14:01   ` Richard Cochran
2020-07-14 14:27     ` Sergey Organov
2020-07-14 16:28 ` [PATCH v3 " Sergey Organov
2020-07-16 18:24   ` Jakub Kicinski
2020-07-16 20:38     ` Sergey Organov
2020-07-16 21:06       ` Jakub Kicinski
2020-07-16 21:18         ` Sergey Organov
2020-07-15 15:42 ` [PATCH net-next v2 0/4] net: fec: a few improvements Sergey Organov
2020-07-15 15:42   ` [PATCH net-next v2 1/4] net: fec: enable to use PPS feature without time stamping Sergey Organov
2020-07-15 15:42   ` [PATCH net-next v2 2/4] net: fec: initialize clock with 0 rather than current kernel time Sergey Organov
2020-07-15 15:42   ` [PATCH net-next v2 3/4] net: fec: get rid of redundant code in fec_ptp_set() Sergey Organov
2020-07-15 15:43   ` [PATCH net-next v2 4/4] net: fec: replace snprintf() with strlcpy() in fec_ptp_init() Sergey Organov
2020-07-16  3:00   ` [EXT] [PATCH net-next v2 0/4] net: fec: a few improvements Andy Duan
2020-07-16 18:37     ` Jakub Kicinski

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