netdev - Re: [PATCH net-next v6 07/16] net_tstamp: Add TIMESTAMPING SOFTWARE and HARDWARE mask

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Message-ID: <CAF=yD-LCNGcCMqpAbV1HfyVdjH7Gj-_tTwsS=08Y5CC6bqBd=w@mail.gmail.com>
Date: Tue, 24 Oct 2023 10:21:15 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Köry Maincent <kory.maincent@...tlin.com>
Cc: Florian Fainelli <florian.fainelli@...adcom.com>, 
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, Andrew Lunn <andrew@...n.ch>, 
	Heiner Kallweit <hkallweit1@...il.com>, Russell King <linux@...linux.org.uk>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Richard Cochran <richardcochran@...il.com>, Radu Pirea <radu-nicolae.pirea@....nxp.com>, 
	Jay Vosburgh <j.vosburgh@...il.com>, Andy Gospodarek <andy@...yhouse.net>, 
	Nicolas Ferre <nicolas.ferre@...rochip.com>, Claudiu Beznea <claudiu.beznea@...on.dev>, 
	Jonathan Corbet <corbet@....net>, Horatiu Vultur <horatiu.vultur@...rochip.com>, 
	UNGLinuxDriver@...rochip.com, Simon Horman <horms@...nel.org>, 
	Vladimir Oltean <vladimir.oltean@....com>, Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org, Maxime Chevallier <maxime.chevallier@...tlin.com>
Subject: Re: [PATCH net-next v6 07/16] net_tstamp: Add TIMESTAMPING SOFTWARE
 and HARDWARE mask

On Tue, Oct 24, 2023 at 9:40 AM Köry Maincent <kory.maincent@...tlin.com> wrote:
>
> On Thu, 19 Oct 2023 10:48:04 -0400
> Willem de Bruijn <willemdebruijn.kernel@...il.com> wrote:
>
> > On Thu, Oct 19, 2023 at 10:29 AM Kory Maincent
> > <kory.maincent@...tlin.com> wrote:
> > >
> > > Timestamping software or hardware flags are often used as a group,
> > > therefore adding these masks will easier future use.
> >
> > This assumes that device support for timestamping is often symmetric:
> > a device supports both rx and tx, or neither.
> >
> > All devices support software receive timestamping, as that timestamp
> > is taken in the core network stack. But to support transmit timestamps
> > drivers have to call sbk_tstamp_tx in their ndo_start_xmit.
>
> Yes, and in that software only case they often call ethtool_op_get_ts_info to
> fill the timestamp info.
>
> There is several drivers that support hardware and software timestamp, these
> mask could be useful for these. In case of asymmetric support we can still use
> the SOF_TIMESTAMPING_RX/TX_SOFTWARE flags.
>
> I forgot to specify, in the commit message but this patch is mainly to ease
> the next patch of this series to deal with software/hardware time stamping.
> Maybe you prefer to have this squash into next patch as had suggested Florian
> in last version.

Thanks. I did not see such use in net/ or in my experience of using
setsockopt SO_TIMESTAMPING.

But I had not considered net device get_ts_info. It would be useful there.

Slight preference from me to keep this a separate patch, as it applies
not only to the use case in your follow-on patch.