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From:   Rahul Rameshbabu <rrameshbabu@nvidia.com>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     =?utf-8?Q?K=C3=B6ry?= Maincent <kory.maincent@bootlin.com>,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <florian.fainelli@broadcom.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@broadcom.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Richard Cochran <richardcochran@gmail.com>,
        Radu Pirea <radu-nicolae.pirea@oss.nxp.com>,
        Jay Vosburgh <j.vosburgh@gmail.com>,
        Andy Gospodarek <andy@greyhouse.net>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Claudiu Beznea <claudiu.beznea@tuxon.dev>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        UNGLinuxDriver@microchip.com, Simon Horman <horms@kernel.org>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org,
        Maxime Chevallier <maxime.chevallier@bootlin.com>
Subject: Re: [PATCH net-next v7 15/16] net: ethtool: ts: Let the active time
 stamping layer be selectable
References: <20231120121440.3274d44c@kmaincent-XPS-13-7390>
        <20231120120601.ondrhbkqpnaozl2q@skbuf>
        <20231120144929.3375317e@kmaincent-XPS-13-7390>
        <20231120142316.d2emoaqeej2pg4s3@skbuf> <20231120093723.4d88fb2a@kernel.org>
        <157c68b0-687e-4333-9d59-fad3f5032345@lunn.ch>
        <20231120105148.064dc4bd@kernel.org> <20231120195858.wpaymolv6ws4hntp@skbuf>
        <20231120134551.30d0306c@kernel.org>
        <20231129210959.19e1e2b7@kmaincent-XPS-13-7390>
        <20231129203700.ckpkc4r5bwwudwpf@skbuf>
        <20231129230034.7301d8b2@kmaincent-XPS-13-7390>
        <20231129155613.58c4b93b@kernel.org>
Date:   Wed, 29 Nov 2023 16:06:38 -0800
In-Reply-To: <20231129155613.58c4b93b@kernel.org> (Jakub Kicinski's message of
        "Wed, 29 Nov 2023 15:56:13 -0800")
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On Wed, 29 Nov, 2023 15:56:13 -0800 Jakub Kicinski <kuba@kernel.org> wrote:
> On Wed, 29 Nov 2023 23:00:34 +0100 K=C3=B6ry Maincent wrote:
>> > Not sure why you say "not used", though. Are you not planning to expos=
e
>> > the qualifier as an attribute to the listing of hwtstamp providers
>> > offered to user space by ETHTOOL_MSG_TSINFO_GET? =20
>>=20
>> Yes I will, I was just saying that all the PHC would be set as precise f=
or now.
>> Approximate timestamp quality won't be used because IIUC there are no NI=
C driver
>> supporting it yet.
>
> Agreed that we should add the attr from the start.
>
> Maybe we can ask/work with Rahul <rrameshbabu@nvidia.com>
> to implement the right thing in mlx5?

Thanks for looping me in. We were already looking at this patch series
out of interest. I saw your suggestion to rephrase "MAC / DMA" as
"precise / approximate", which we really like for mlx5 devices because
our "approximate" timestamping logic is not exactly a "MAC" timestamp
but its not a port timestamp that has the greater precision we use. I
have a task already for implementing support for this ethtool attribute.
If folks here are open to it, I can add mlx5 support for both modes in
this patch series for the next revision that will entail the discussed
changes.

>
> Failing that we can mark mlx5 as imprecise, until its sorted out.
> So that we have both types in the tree.

--
Thanks,

Rahul Rameshbabu