Re: [PATCH RFC V1 net-next 3/4] net: Let the active time stamping layer be selectable.

From: Richard Cochran <richardcochran@gmail.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Andrew Lunn <andrew@lunn.ch>, David Miller <davem@davemloft.net>,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Joakim Zhang <qiangqing.zhang@nxp.com>,
	Kurt Kanzenbach <kurt@linutronix.de>,
	Miroslav Lichvar <mlichvar@redhat.com>,
	Vladimir Oltean <vladimir.oltean@nxp.com>
Subject: Re: [PATCH RFC V1 net-next 3/4] net: Let the active time stamping layer be selectable.
Date: Mon, 3 Jan 2022 17:42:15 -0800	[thread overview]
Message-ID: <20220104014215.GA20062@hoboy.vegasvil.org> (raw)
In-Reply-To: <YdOMlfbMH9b553V/@shell.armlinux.org.uk>

On Mon, Jan 03, 2022 at 11:53:57PM +0000, Russell King (Oracle) wrote:
> On Mon, Jan 03, 2022 at 03:25:54PM -0800, Richard Cochran wrote:
> > Make the sysfs knob writable, and add checks in the ioctl and time
> > stamping paths to respect the currently selected time stamping layer.
> > 
> > Signed-off-by: Richard Cochran <richardcochran@gmail.com>
> 
> As I stated for patch 2, this patch will break mvpp2 PTP support,
> since as soon as we bind a PHY, whether or not it supports PTP, you
> will switch "selected_timestamping_layer" to be PHY mode PTP, and
> direct all PTP calls to the PHY layer whether or not the PHY has
> PTP support, away from the MAC layer.

Oh, that was a brain fart of mine.

I'll amend that to switch selected_timestamping_layer only if the PHY
does support time stamping.

IMO, the default should be PHY because up until now the PHY layer was
prefered.

Or would you say the MAC layer should take default priority?

(that may well break some existing systems)

Thanks,
Richard