netdev - Re: [PATCH net-next 0/3] Unlock new potential in SJA1105 with PTP system timestamping

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Date:   Mon, 11 Nov 2019 15:19:26 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 0/3] Unlock new potential in SJA1105 with PTP
 system timestamping

On Sat, 9 Nov 2019 at 17:19, Richard Cochran <richardcochran@...il.com> wrote:
>
> On Sat, Nov 09, 2019 at 01:32:21PM +0200, Vladimir Oltean wrote:
> > The SJA1105 being an automotive switch means it is designed to live in a
> > set-and-forget environment, far from the configure-at-runtime nature of
> > Linux. Frequently resetting the switch to change its static config means
> > it loses track of its PTP time, which is not good.
> >
> > This patch series implements PTP system timestamping for this switch
> > (using the API introduced for SPI here:
> > https://www.mail-archive.com/netdev@vger.kernel.org/msg316725.html),
> > adding the following benefits to the driver:
> > - When under control of a user space PTP servo loop (ptp4l, phc2sys),
> >   the loss of sync during a switch reset is much more manageable, and
> >   the switch still remains in the s2 (locked servo) state.
> > - When synchronizing the switch using the software technique (based on
> >   reading clock A and writing the value to clock B, as opposed to
> >   relying on hardware timestamping), e.g. by using phc2sys, the sync
> >   accuracy is vastly improved due to the fact that the actual switch PTP
> >   time can now be more precisely correlated with something of better
> >   precision (CLOCK_REALTIME). The issue is that SPI transfers are
> >   inherently bad for measuring time with low jitter, but the newly
> >   introduced API aims to alleviate that issue somewhat.
> >
> > This series is also a requirement for a future patch set that adds full
> > time-aware scheduling offload support for the switch.
> >
> > Vladimir Oltean (3):
> >   net: dsa: sja1105: Implement the .gettimex64 system call for PTP
> >   net: dsa: sja1105: Restore PTP time after switch reset
> >   net: dsa: sja1105: Disallow management xmit during switch reset
>
> For the series:
>
> Acked-by: Richard Cochran <richardcochran@...il.com>

Thanks Richard.

David, I noticed you put these patches in Patchwork in the 'Needs
Review / ACK' state. Do you need more in-depth review, or did you just
miss Richard's tag, since Patchwork ignores them if they're posted on
the cover letter?

[ in fact, I have a similar question for the "Accomodate DSA front-end
into Ocelot" series, which also has 1 R and 1 A on the cover letter ]

Regards,
-Vladimir