netdev - Re: [PATCH RFC net-next] net: phy: add Marvell PHY PTP support [multicast/DSA issues]

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Message-ID: <Y/3ubSj5+2C5xbZu@shell.armlinux.org.uk>
Date:   Tue, 28 Feb 2023 12:07:09 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     Köry Maincent <kory.maincent@...tlin.com>,
        andrew@...n.ch, davem@...emloft.net, f.fainelli@...il.com,
        hkallweit1@...il.com, kuba@...nel.org, netdev@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>
Subject: Re: [PATCH RFC net-next] net: phy: add Marvell PHY PTP support
 [multicast/DSA issues]

On Mon, Feb 27, 2023 at 12:19:22PM -0800, Richard Cochran wrote:
> On Mon, Feb 27, 2023 at 08:09:05PM +0000, Russell King (Oracle) wrote:
> 
> > Looking at that link, I'm only seeing that message, with none of
> > the patches nor the discussion. Digging back in my mailbox, I
> > find that the patches weren't threaded to the cover message, which
> > makes it quite difficult to go back and review the discussion.
> 
> Sorry about that.  By accident I omitted --thread=shallow that time.
> 
> > Looking back briefly at the discussion on patch 3, was the reason
> > this approach died due to the request to have something more flexible,
> > supporting multiple hardware timestamps per packet?
> 
> I still think the approach will work, but I guess I got distracted
> with other stuff and forgot about it.
> 
> The "multiple hardware timestamps per packet" is a nice idea, but it
> would require a new user API, and so selectable MAC/PHY on the
> existing API is still needed.

I agree - even when we have support for multiple hardware timestamps,
we still need the existing API to work in a sensible way, and we need
a way to choose which hardware timestamp we want the existing API to
report.

So yes, it's a nice idea to support multiple hardware timestamps, but
I think that's an entirely separate problem to solving the current
issue, which is a blocking issue to adding support for PTP on some
platforms.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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