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From: Vladimir Oltean <vladimir.oltean@nxp.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: "Russell King (Oracle)" <linux@armlinux.org.uk>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"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, "Jacob Keller" <jacob.e.keller@intel.com>
Subject: Re: [PATCH net-next RFC v4 2/5] net: Expose available time stamping layers to user space.
Date: Fri, 19 May 2023 16:28:02 +0300	[thread overview]
Message-ID: <20230519132802.6f2v47zuz7omvazy@skbuf> (raw)
In-Reply-To: <20230512103852.64fd608b@kernel.org>

On Fri, May 12, 2023 at 10:38:52AM -0700, Jakub Kicinski wrote:
> On Fri, 12 May 2023 13:29:11 +0300 Vladimir Oltean wrote:
> > On Thu, May 11, 2023 at 04:16:25PM -0700, Jakub Kicinski wrote:
> > > > I mean, I can't ignore the fact that there are NICs that can provide
> > > > 2-step TX timestamps at line rate for all packets (not just PTP) for
> > > > line rates exceeding 10G, in band with the descriptor in its TX
> > > > completion queue. I don't want to give any names, just to point out
> > > > that there isn't any inherent limitation in the technology.  
> > > 
> > > Oh, you should tell me, maybe off-list then. 'Cause I don't know any.  
> > 
> > I hope the examples given in private will make you reconsider the
> > validity of my argument about DMA timestamps.
> 
> I may have lost track of what the argument is. There are devices
> which will provide a DMA stamp for Tx and Rx. We need an API that'll
> inform the user about it. 
> 
> To be clear I'm talking about drivers which are already in the tree,
> not opening the door for some shoddy new HW in.

So this is circling back to my original question (with emphasis on the
last part):

| Which drivers provide DMA timestamps, and how do they currently signal
| that they do this? Do they do this for all packets that get timestamped,
| or for "some"?

https://lore.kernel.org/netdev/20230511203646.ihljeknxni77uu5j@skbuf/

If only "some" packets (unpredictable which) get DMA timestamps when
a MAC timestamp isn't available, what UAPI can satisfactorily describe
that? And who would want that?

  parent reply	other threads:[~2023-05-19 13:28 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
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 [this message]
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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