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

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Date:   Mon, 27 Feb 2023 15:20:05 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Köry Maincent <kory.maincent@...tlin.com>
Cc:     andrew@...n.ch, davem@...emloft.net, f.fainelli@...il.com,
        hkallweit1@...il.com, kuba@...nel.org, netdev@...r.kernel.org,
        richardcochran@...il.com,
        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 03:40:37PM +0100, Köry Maincent wrote:
> Hello RMK,
> 
> > Hence why I'm at the point of giving up; I don't see that PTP will be
> > of very limited benefit on my network with all these issues, and in
> > any case, NTP has been "good enough" for the last 20+ years.  Given
> > that only a limited number of machines will be able to implement PTP
> > support anyway, NTP will have to run along side it.
> 
> I see this patch has been abandoned.
> I am testing it with a ZynqMP board (macb ethernet) and it seems to more or
> less work. It got tx timestamp timeout at initialization but after some times
> (~20 seconds) ptp4l manages to set it working. Also the IEEE 802.3
> network PTP mode is not working, it constantly throw rx timestamp overrun
> errors.
> I will aim at fixing these issues and adding support to interrupts. It would be
> good to have it accepted mainline. What do you think is missing for that?

It isn't formally abandoned, but is permanently on-hold as merging
Marvell PHY PTP support into mainline _will_ regress the superior PTP
support on the Macchiatobin platform for the reasons outlined in:

https://lore.kernel.org/netdev/20200729220748.GW1605@shell.armlinux.org.uk/

Attempting to fix this problem was basically rejected by the PTP
maintainer, and thus we're at a deadlock over the issue, and Marvell
PHY PTP support can never be merged into mainline.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!