From: Jakub Kicinski <kuba@kernel•org>
To: Andrew Lunn <andrew@lunn•ch>
Cc: "Vladimir Oltean" <vladimir.oltean@nxp•com>,
"Russell King (Oracle)" <linux@armlinux•org.uk>,
"Köry Maincent" <kory.maincent@bootlin•com>,
netdev@vger•kernel.org, glipus@gmail•com,
maxime.chevallier@bootlin•com, vadim.fedorenko@linux•dev,
richardcochran@gmail•com, gerhard@engleder-embedded•com,
thomas.petazzoni@bootlin•com, krzysztof.kozlowski+dt@linaro•org,
robh+dt@kernel•org
Subject: Re: [PATCH net-next RFC v4 2/5] net: Expose available time stamping layers to user space.
Date: Wed, 17 May 2023 13:07:06 -0700 [thread overview]
Message-ID: <20230517130706.3432203b@kernel.org> (raw)
In-Reply-To: <2f89e35e-b1c9-4e08-9f60-73a96cc6e51a@lunn.ch>
On Wed, 17 May 2023 21:46:43 +0200 Andrew Lunn wrote:
> As i said in an earlier thread, with a bit of a stretch, there could
> be 7 places to take time stamps in the system. We need some sort of
> identifier to indicate which of these stampers to use.
>
> Is clock ID unique? In a switch, i think there could be multiple
> stampers, one per MAC port, sharing one clock? So you actually need
> more than a clock ID.
Clock ID is a bit vague too, granted, but in practice clock ID should
correspond to the driver fairly well? My thinking was - use clock ID
to select the (silicon) device, use a different attribute to select
the stamping point.
IOW try to use the existing attribute before inventing a new one.
> Also, 'By the standard - stamping happens under the MAC'. Which MAC?
> There can be multple MAC's in the pipeline. MACSEC and rate adaptation
> in the PHY are often implemented by the PHY having a MAC
> reconstituting the frame from the bitstream and putting it into a
> queue. Rate adaptation can then be performed by the PHY by sending
> pause frames to the 'primary' MAC to slow it down. MACSEC in the PHY
> takes frames in the queues and if they match a filter they get
> encrypted. The PHY then takes the frame out of the queue and passes
> them to a second MAC in the PHY which creates a bitstream and then to
> a 'PHY' to generate signals for the line.
>
> In this sort of setup, you obviously don't want the 'primary' MAC
> doing the stamping. You want the MAC nearest to the line, or better
> still the 'PHY' within the PHY just before the line.
For a PHY "always use the point closest to the wire" makes sense.
For DMA we'd have a different set of priorities - precision vs
volume vs 1-step / 2-step; but all from the same clock. I think
that we may want to defer figuring out selection within a single
clock for now, to make some progress.
next prev parent reply other threads:[~2023-05-17 20:07 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-06 17:33 [PATCH net-next RFC v4 0/5] net: Make MAC/PHY time stamping selectable Köry Maincent
2023-04-06 17:33 ` [PATCH net-next RFC v4 1/5] net: ethtool: Refactor identical get_ts_info implementations Köry Maincent
2023-04-12 13:16 ` Vladimir Oltean
2023-04-12 13:49 ` Köry Maincent
2023-04-12 16:56 ` Richard Cochran
2023-04-06 17:33 ` [PATCH net-next RFC v4 2/5] net: Expose available time stamping layers to user space Köry Maincent
2023-04-07 1:46 ` Jakub Kicinski
2023-04-07 8:58 ` Köry Maincent
2023-04-07 14:26 ` Jakub Kicinski
2023-04-07 14:44 ` Jakub Kicinski
2023-05-17 19:58 ` Jacob Keller
2023-04-12 10:50 ` Michael Walle
2023-04-12 11:08 ` Vladimir Oltean
2023-04-12 11:12 ` Michael Walle
2023-04-12 12:19 ` Köry Maincent
2023-05-11 20:36 ` Vladimir Oltean
2023-05-11 20:50 ` Andrew Lunn
2023-05-11 20:55 ` Russell King (Oracle)
2023-05-11 21:02 ` Vladimir Oltean
2023-05-11 22:09 ` Jakub Kicinski
2023-05-11 23:07 ` Vladimir Oltean
2023-05-11 23:16 ` Jakub Kicinski
2023-05-12 10:29 ` Vladimir Oltean
2023-05-12 17:38 ` Jakub Kicinski
2023-05-17 19:19 ` Jakub Kicinski
2023-05-17 19:46 ` Andrew Lunn
2023-05-17 20:07 ` Jakub Kicinski [this message]
2023-09-04 15:22 ` Köry Maincent
2023-09-04 17:47 ` Richard Cochran
2023-09-05 18:47 ` Jakub Kicinski
2023-09-05 20:29 ` Andrew Lunn
2023-09-06 9:22 ` Köry Maincent
2023-09-07 9:29 ` Russell King (Oracle)
2023-05-19 13:28 ` Vladimir Oltean
2023-05-19 20:22 ` Jakub Kicinski
2023-05-22 3:56 ` Zulkifli, Muhammad Husaini
2023-05-22 20:04 ` Richard Cochran
2023-05-22 20:21 ` Jakub Kicinski
2023-05-23 3:54 ` Richard Cochran
2023-05-17 22:01 ` Jacob Keller
2023-05-17 22:13 ` Jacob Keller
2023-05-17 22:46 ` Richard Cochran
2023-05-18 23:23 ` Jacob Keller
2023-05-19 12:50 ` Andrew Lunn
2023-05-19 13:50 ` Richard Cochran
2023-05-19 15:18 ` Andrew Lunn
2023-04-08 14:06 ` Richard Cochran
2023-04-06 17:33 ` [PATCH net-next RFC v4 3/5] dt-bindings: net: phy: add timestamp preferred choice property Köry Maincent
2023-04-12 13:14 ` Vladimir Oltean
2023-04-12 13:44 ` Köry Maincent
2023-04-29 17:42 ` Vladimir Oltean
2023-05-02 9:10 ` Köry Maincent
2023-05-11 13:10 ` Vladimir Oltean
2023-05-11 13:25 ` Köry Maincent
2023-05-11 13:56 ` Vladimir Oltean
2023-05-11 14:22 ` Köry Maincent
2023-04-12 14:14 ` Krzysztof Kozlowski
2023-04-06 17:33 ` [PATCH net-next RFC v4 4/5] net: Let the active time stamping layer be selectable Köry Maincent
2023-04-07 1:47 ` Jakub Kicinski
2023-04-29 17:58 ` Vladimir Oltean
2023-05-02 11:05 ` Köry Maincent
2023-05-11 13:48 ` Vladimir Oltean
2023-05-11 15:36 ` Jakub Kicinski
2023-05-11 15:56 ` Vladimir Oltean
2023-05-11 16:25 ` Jakub Kicinski
2023-05-11 20:54 ` Vladimir Oltean
2023-05-11 23:08 ` Jakub Kicinski
2023-05-11 23:18 ` Vladimir Oltean
2023-05-11 23:35 ` Jakub Kicinski
2023-05-15 9:04 ` Köry Maincent
2023-05-16 19:28 ` Jakub Kicinski
2023-05-11 21:06 ` Russell King (Oracle)
2023-05-11 22:54 ` Jakub Kicinski
2023-05-17 22:19 ` Jacob Keller
2023-04-06 17:33 ` [PATCH net-next RFC v4 5/5] net: fix up drivers WRT phy time stamping Köry Maincent
2023-04-06 17:59 ` [PATCH net-next RFC v4 0/5] net: Make MAC/PHY time stamping selectable Köry Maincent
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