From: Jacob Keller <jacob.e.keller@intel.com>
To: "Jakub Kicinski" <kuba@kernel.org>,
"Köry Maincent" <kory.maincent@bootlin.com>
Cc: Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <florian.fainelli@broadcom.com>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-doc@vger.kernel.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
"David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
"Jonathan Corbet" <corbet@lwn.net>,
Jay Vosburgh <j.vosburgh@gmail.com>,
Andy Gospodarek <andy@greyhouse.net>,
Nicolas Ferre <nicolas.ferre@microchip.com>,
"Claudiu Beznea" <claudiu.beznea@tuxon.dev>,
Horatiu Vultur <horatiu.vultur@microchip.com>,
<UNGLinuxDriver@microchip.com>,
"Broadcom internal kernel review list"
<bcm-kernel-feedback-list@broadcom.com>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
Russell King <linux@armlinux.org.uk>,
Richard Cochran <richardcochran@gmail.com>,
Radu Pirea <radu-nicolae.pirea@oss.nxp.com>,
Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Vladimir Oltean <vladimir.oltean@nxp.com>,
Michael Walle <michael@walle.cc>,
Maxime Chevallier <maxime.chevallier@bootlin.com>
Subject: Re: [PATCH net-next v5 08/16] net: ethtool: Add a command to expose current time stamping layer
Date: Mon, 16 Oct 2023 16:03:13 -0700 [thread overview]
Message-ID: <bae82fe3-56da-49df-94b6-1e2998f86503@intel.com> (raw)
In-Reply-To: <20231016100313.36d4eab9@kernel.org>
On 10/16/2023 10:03 AM, Jakub Kicinski wrote:
> On Mon, 16 Oct 2023 18:23:07 +0200 Köry Maincent wrote:
>>> What's the reason for timestamp precision differences?
>>> My understanding so far was the the differences come from:
>>> 1. different stamping device (i.e. separate "piece of silicon",
>>> accessed over a different bus, with different PHC etc.)
>>> 2. different stamping point (MAC vs DMA)
>>>
>>> I don't think any "integrated" device would support stamps which
>>> differ under category 1.
>>
>> It was a case reported by Maxime on v3:
>> https://lore.kernel.org/netdev/20230324112541.0b3dd38a@pc-7.home/
>
> IMHO this talks about how clock control/disciplining works which
> is a somewhat independent topic of timestamping.
The thread in question mentions that the device has two modes, one which
has higher precision for the timestamps, and one which has better
precision on frequency adjustments. I don't know the details for why the
hardware has this behavior, but being able to switch between the two
timestamp modes has value as described by the thread.
I'm not sure how to represent that in such an API because both modes
seem to capture the timestamp at the MAC.
next prev parent reply other threads:[~2023-10-16 23:03 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-09 15:51 [PATCH net-next v5 00/16] net: Make timestamping selectable Köry Maincent
2023-10-09 15:51 ` [PATCH net-next v5 01/16] net: Convert PHYs hwtstamp callback to use kernel_hwtstamp_config Köry Maincent
2023-10-09 21:02 ` Florian Fainelli
2023-10-10 15:37 ` Simon Horman
2023-10-11 8:27 ` Köry Maincent
2023-10-20 20:23 ` kernel test robot
2023-10-09 15:51 ` [PATCH net-next v5 02/16] net: phy: Remove the call to phy_mii_ioctl in phy_hwstamp_get/set Köry Maincent
2023-10-09 21:04 ` Florian Fainelli
2023-10-09 15:51 ` [PATCH net-next v5 03/16] net: ethtool: Refactor identical get_ts_info implementations Köry Maincent
2023-10-09 19:56 ` kernel test robot
2023-10-09 21:06 ` Florian Fainelli
2023-10-11 21:41 ` Jay Vosburgh
2023-10-09 15:51 ` [PATCH net-next v5 04/16] net: macb: Convert to ndo_hwtstamp_get() and ndo_hwtstamp_set() Köry Maincent
2023-10-09 21:08 ` Florian Fainelli
2023-10-09 15:51 ` [PATCH net-next v5 05/16] net: Make dev_set_hwtstamp_phylib accessible Köry Maincent
2023-10-09 21:09 ` Florian Fainelli
2023-10-10 7:40 ` Köry Maincent
2023-10-09 15:51 ` [PATCH net-next v5 06/16] net_tstamp: Add TIMESTAMPING SOFTWARE and HARDWARE mask Köry Maincent
2023-10-09 21:11 ` Florian Fainelli
2023-10-09 15:51 ` [PATCH net-next v5 07/16] net: phy: micrel: fix ts_info value in case of no phc Köry Maincent
2023-10-09 21:14 ` Florian Fainelli
2023-10-09 15:51 ` [PATCH net-next v5 08/16] net: ethtool: Add a command to expose current time stamping layer Köry Maincent
2023-10-09 21:20 ` Florian Fainelli
2023-10-10 8:23 ` Köry Maincent
2023-10-13 16:00 ` Jakub Kicinski
2023-10-13 16:11 ` Andrew Lunn
2023-10-16 10:41 ` Köry Maincent
2023-10-16 14:22 ` Jakub Kicinski
2023-10-16 15:00 ` Köry Maincent
2023-10-16 15:43 ` Jakub Kicinski
2023-10-16 16:23 ` Köry Maincent
2023-10-16 17:03 ` Jakub Kicinski
2023-10-16 23:03 ` Jacob Keller [this message]
2023-10-17 9:21 ` Köry Maincent
2023-10-16 23:50 ` Richard Cochran
2023-10-17 8:29 ` Köry Maincent
2023-10-13 16:14 ` Vladimir Oltean
2023-10-13 16:30 ` Jakub Kicinski
2023-10-13 17:09 ` Vladimir Oltean
2023-10-13 17:46 ` Jakub Kicinski
2023-10-13 17:56 ` Vladimir Oltean
2023-10-13 20:15 ` Jakub Kicinski
2023-10-09 15:51 ` [PATCH net-next v5 09/16] netlink: specs: Introduce new netlink command to get current timestamp Köry Maincent
2023-10-09 21:21 ` Florian Fainelli
2023-10-10 8:40 ` Köry Maincent
2023-10-09 15:51 ` [PATCH net-next v5 10/16] net: ethtool: Add a command to list available time stamping layers Köry Maincent
2023-10-13 22:52 ` kernel test robot
2023-10-09 15:51 ` [PATCH net-next v5 11/16] netlink: specs: Introduce new netlink " Köry Maincent
2023-10-09 21:22 ` Florian Fainelli
2023-10-09 15:51 ` [PATCH net-next v5 12/16] net: Replace hwtstamp_source by timestamping layer Köry Maincent
2023-10-09 21:23 ` Florian Fainelli
2023-10-09 15:51 ` [PATCH net-next v5 13/16] net: Change the API of PHY default timestamp to MAC Köry Maincent
2023-10-09 22:23 ` Florian Fainelli
2023-10-10 15:52 ` Simon Horman
2023-10-13 1:37 ` kernel test robot
2023-10-09 15:51 ` [PATCH net-next v5 14/16] net: ethtool: ts: Update GET_TS to reply the current selected timestamp Köry Maincent
2023-10-09 15:51 ` [PATCH net-next v5 15/16] net ethtool: net: Let the active time stamping layer be selectable Köry Maincent
2023-10-09 21:28 ` Florian Fainelli
2023-10-10 8:31 ` Köry Maincent
2023-10-09 15:51 ` [PATCH net-next v5 16/16] netlink: specs: Introduce time stamping set command Köry Maincent
2023-10-09 21:29 ` Florian Fainelli
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