Re: [PATCH RFC net-next] net: phy: add Marvell PHY PTP support

From: Richard Cochran <richardcochran@gmail.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org
Subject: Re: [PATCH RFC net-next] net: phy: add Marvell PHY PTP support
Date: Thu, 30 Jul 2020 12:32:45 -0700	[thread overview]
Message-ID: <20200730193245.GB6621@hoboy> (raw)
In-Reply-To: <20200730183800.GD1551@shell.armlinux.org.uk>

On Thu, Jul 30, 2020 at 07:38:00PM +0100, Russell King - ARM Linux admin wrote:
> What I ended up doing was:
> 
>         if (ops->get_ts_info) {
>                 ret = ops->get_ts_info(dev, info);
>                 if (ret != -EOPNOTSUPP)
>                         return ret;
>         }
>         if (phy_has_tsinfo(phydev))
>                 return phy_ts_info(phydev, info);
> ...
> 
> which gives the MAC first refusal.  If the MAC wishes to defer to
> phylib or the default, it can just return -EOPNOTSUPP.

I guess that makes sense.  If someone designs a board that happens to
have a PHY with unwanted time stamping fcunctionality, then at least
the MAC time stamping function will work.  If the designers really
want PHY time stamping, then they are likely to have to patch the MAC
driver in any case.

So I'm not against such a change.  It would be important to keep the
current "PHY-friendly" MAC drivers still friendly, and so they would
need patching as part of the change.

Thanks,
Richard