netdev - Re: [PATCH v2 3/4] net: Let the active time stamping layer be selectable.

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Message-ID: <94544cd0-18da-40d1-8691-66e50d42bfb4@lunn.ch>
Date:   Sat, 4 Mar 2023 20:46:05 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
Cc:     Köry Maincent <kory.maincent@...tlin.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-omap@...r.kernel.org, Michael Walle <michael@...le.cc>,
        Richard Cochran <richardcochran@...il.com>,
        thomas.petazzoni@...tlin.com, Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Joakim Zhang <qiangqing.zhang@....com>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        UNGLinuxDriver@...rochip.com,
        Grygorii Strashko <grygorii.strashko@...com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Minghao Chi <chi.minghao@....com.cn>,
        Jie Wang <wangjie125@...wei.com>,
        Guangbin Huang <huangguangbin2@...wei.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Wang Yufen <wangyufen@...wei.com>,
        Alexandru Tachici <alexandru.tachici@...log.com>,
        Oleksij Rempel <linux@...pel-privat.de>
Subject: Re: [PATCH v2 3/4] net: Let the active time stamping layer be
 selectable.

> The timestamping part is via the netdev, which is a separate entity,
> and its that entity which is responsible for identifying which PHC it
> is connected to (normally by filling in the phc_index field of
> ethtool_ts_info.)
> 
> Think of is as:
> 
>   netdev ---- timestamping ---- PHC
> 
> since we can have:
> 
>   netdev1 ---- timestamping \
>   netdev2 ---- timestamping -*--- PHC
>   netdev3 ---- timestamping /
> 
> Since the ioctl is to do with requesting what we want the timestamping
> layer to be doing with packets, putting it in ptp_clock_info makes
> very little sense.

So there does not appear to be an object to represent a time stamper?

Should one be added? It looks like it needs two ops hwtstamp_set() and
hwtstamp_get(). It would then be registered with the ptp core. And
then the rest of what i said would apply...

	Andrew