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From: "Y.b. Lu" <yangbo.lu@nxp.com>
To: Richard Cochran <richardcochran@gmail.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-kselftest@vger.kernel.org"
	<linux-kselftest@vger.kernel.org>,
	"mptcp@lists.linux.dev" <mptcp@lists.linux.dev>,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Mat Martineau <mathew.j.martineau@linux.intel.com>,
	Matthieu Baerts <matthieu.baerts@tessares.net>,
	Shuah Khan <shuah@kernel.org>, Michal Kubecek <mkubecek@suse.cz>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>, Rui Sousa <rui.sousa@nxp.com>,
	Sebastien Laveze <sebastien.laveze@nxp.com>
Subject: RE: [net-next, v5, 08/11] net: sock: extend SO_TIMESTAMPING for PHC binding
Date: Mon, 5 Jul 2021 08:19:30 +0000	[thread overview]
Message-ID: <DB7PR04MB50174906EE8CCEB4A02F4C17F81C9@DB7PR04MB5017.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20210704133331.GA4268@hoboy.vegasvil.org>

Hi Richard,

> -----Original Message-----
> From: Richard Cochran <richardcochran@gmail.com>
> Sent: 2021年7月4日 21:34
> To: Y.b. Lu <yangbo.lu@nxp.com>
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-kselftest@vger.kernel.org; mptcp@lists.linux.dev; David S . Miller
> <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Mat Martineau
> <mathew.j.martineau@linux.intel.com>; Matthieu Baerts
> <matthieu.baerts@tessares.net>; Shuah Khan <shuah@kernel.org>; Michal
> Kubecek <mkubecek@suse.cz>; Florian Fainelli <f.fainelli@gmail.com>;
> Andrew Lunn <andrew@lunn.ch>; Rui Sousa <rui.sousa@nxp.com>; Sebastien
> Laveze <sebastien.laveze@nxp.com>
> Subject: Re: [net-next, v5, 08/11] net: sock: extend SO_TIMESTAMPING for
> PHC binding
> 
> On Wed, Jun 30, 2021 at 04:11:59PM +0800, Yangbo Lu wrote:
> > Since PTP virtual clock support is added, there can be several PTP
> > virtual clocks based on one PTP physical clock for timestamping.
> >
> > This patch is to extend SO_TIMESTAMPING API to support PHC (PTP
> > Hardware Clock) binding by adding a new flag
> > SOF_TIMESTAMPING_BIND_PHC. When PTP virtual clocks are in use, user
> > space can configure to bind one for timestamping, but PTP physical
> > clock is not supported and not needed to bind.
> 
> Would it not be better to simply bind automatically?
> 
> Like this pseudo code:
> 
> 	if (hw_timestamping_requested() && interface_is_vclock()) {
> 		bind_vclock();
> 	}
> 
> It would be great to avoid forcing user space to use a new option.
> 
> Especially because NOT setting the option makes no sense.  Or maybe there is
> a use case for omitting the option?
> 
> 
> Thoughts?

When several ptp virtual clocks are created, the ptp physical clock is guaranteed for free running.

What I think is, for timestamping, if no flag SOF_TIMESTAMPING_BIND_PHC, the timestamping keeps using ptp physical clock.
If application wants to bind one ptp virtual clock for timestamping, the flag SOF_TIMESTAMPING_BIND_PHC should be set and clock index should be provided.
After all, several ptp virtual clocks created are likely for different timescale/use case. There should be a method for any of applications to select the right one to use.

Does it make sense?
Thank you.

> 
> Thanks,
> Richard

  reply	other threads:[~2021-07-05  8:19 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-30  8:11 [net-next, v5, 00/11] ptp: support virtual clocks and timestamping Yangbo Lu
2021-06-30  8:11 ` [net-next, v5, 01/11] ptp: add ptp virtual clock driver framework Yangbo Lu
2021-06-30  8:11 ` [net-next, v5, 02/11] ptp: support ptp physical/virtual clocks conversion Yangbo Lu
2021-07-04 10:25   ` [ptp] becdd56786: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2021-08-07  1:15   ` [net-next, v5, 02/11] ptp: support ptp physical/virtual clocks conversion Vinicius Costa Gomes
2021-08-07 14:22     ` Richard Cochran
2021-08-07 14:43       ` Vladimir Oltean
2021-08-07 20:56         ` Richard Cochran
2021-06-30  8:11 ` [net-next, v5, 03/11] ptp: track available ptp vclocks information Yangbo Lu
2021-06-30  8:11 ` [net-next, v5, 04/11] ptp: add kernel API ptp_get_vclocks_index() Yangbo Lu
2021-06-30  8:11 ` [net-next, v5, 05/11] ethtool: add a new command for getting PHC virtual clocks Yangbo Lu
2021-06-30  8:11 ` [net-next, v5, 06/11] ptp: add kernel API ptp_convert_timestamp() Yangbo Lu
2021-06-30  8:11 ` [net-next, v5, 07/11] mptcp: setsockopt: convert to mptcp_setsockopt_sol_socket_timestamping() Yangbo Lu
2021-06-30  8:11 ` [net-next, v5, 08/11] net: sock: extend SO_TIMESTAMPING for PHC binding Yangbo Lu
2021-07-04 13:33   ` Richard Cochran
2021-07-05  8:19     ` Y.b. Lu [this message]
2021-07-05 18:44       ` Richard Cochran
2021-06-30  8:12 ` [net-next, v5, 09/11] net: socket: support hardware timestamp conversion to PHC bound Yangbo Lu
2021-06-30  8:12 ` [net-next, v5, 10/11] selftests/net: timestamping: support binding PHC Yangbo Lu
2021-06-30  8:12 ` [net-next, v5, 11/11] MAINTAINERS: add entry for PTP virtual clock driver Yangbo Lu
2021-07-01 20:20 ` [net-next, v5, 00/11] ptp: support virtual clocks and timestamping patchwork-bot+netdevbpf

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