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From: Ido Schimmel <idosch@nvidia.com>
To: Richard Cochran <richardcochran@gmail.com>
Cc: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org,
	pabeni@redhat.com, edumazet@google.com, petrm@nvidia.com,
	amcohen@nvidia.com, danieller@nvidia.com, mlxsw@nvidia.com
Subject: Re: [PATCH net-next 0/9] mlxsw: Add PTP support for Spectrum-2 and newer ASICs
Date: Thu, 28 Jul 2022 10:03:17 +0300	[thread overview]
Message-ID: <YuI0tWAXDBE5joAl@shredder> (raw)
In-Reply-To: <YuH9+/7OrCLzb8vJ@hoboy.vegasvil.org>

On Wed, Jul 27, 2022 at 08:09:47PM -0700, Richard Cochran wrote:
> On Wed, Jul 27, 2022 at 05:44:49PM +0300, Ido Schimmel wrote:
> 
> > Right. The hardware can support a TC operation, but I did not find any
> > Linux interfaces to configure it (did I miss something?) nor got any
> > requirements to support it at the moment.
> 
> linuxptp can operate as a TC, but it sounds like your HW does E2E TC
> without any software support.

Yes. I believe linuxptp only implements a two-step transparent clock,
whereas the hardware supports a one-step transparent clock. Like I said,
I'm not aware of any requirements for that at the moment, but I imagine
we would need a per-netdev interface to instruct the kernel/hardware to
adjust the correction field at ingress/egress for specific message
types.

> 
> P2P TC does need SW support, because the ports must generate peer
> delay requests.

Right. The hardware has the ability to add/reduce a number of
nanoseconds (that it gets from software) from the computed latency on a
per-port and ingress/egress basis. 

> 
> Thanks,
> Richard

  reply	other threads:[~2022-07-28  7:04 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-27  6:23 [PATCH net-next 0/9] mlxsw: Add PTP support for Spectrum-2 and newer ASICs Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 1/9] mlxsw: spectrum_ptp: Add helper functions to configure PTP traps Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 2/9] mlxsw: Support CQEv2 for SDQ in Spectrum-2 and newer ASICs Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 3/9] mlxsw: spectrum_ptp: Add PTP initialization / finalization for Spectrum-2 Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 4/9] mlxsw: Query UTC sec and nsec PCI offsets and values Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 5/9] mlxsw: spectrum_ptp: Add implementation for physical hardware clock operations Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 6/9] mlxsw: Send PTP packets as data packets to overcome a limitation Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 7/9] mlxsw: spectrum: Support time stamping on Spectrum-2 Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 8/9] mlxsw: spectrum_ptp: Support SIOCGHWTSTAMP, SIOCSHWTSTAMP ioctls Ido Schimmel
2022-07-27  6:23 ` [PATCH net-next 9/9] mlxsw: spectrum: Support ethtool 'get_ts_info' callback in Spectrum-2 Ido Schimmel
2022-07-27 14:05 ` [PATCH net-next 0/9] mlxsw: Add PTP support for Spectrum-2 and newer ASICs Richard Cochran
2022-07-27 14:48   ` Ido Schimmel
2022-07-27 14:16 ` Richard Cochran
2022-07-27 14:44   ` Ido Schimmel
2022-07-28  3:09     ` Richard Cochran
2022-07-28  7:03       ` Ido Schimmel [this message]
2022-07-29 10:30 ` patchwork-bot+netdevbpf

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