Re: [PATCH v3 3/5] net: Let the active time stamping layer be selectable.

From: Vladimir Oltean <vladimir.oltean@nxp.com>
To: Michael Walle <michael@walle.cc>
Cc: "Horatiu Vultur" <horatiu.vultur@microchip.com>,
	"Köry Maincent" <kory.maincent@bootlin.com>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-omap@vger.kernel.org,
	"Maxime Chevallier" <maxime.chevallier@bootlin.com>,
	"Richard Cochran" <richardcochran@gmail.com>,
	thomas.petazzoni@bootlin.com,
	"Russell King" <linux@armlinux.org.uk>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Jay Vosburgh" <j.vosburgh@gmail.com>,
	"Veaceslav Falico" <vfalico@gmail.com>,
	"Andy Gospodarek" <andy@greyhouse.net>,
	"Claudiu Manoil" <claudiu.manoil@nxp.com>,
	"Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	UNGLinuxDriver@microchip.com,
	"Minghao Chi" <chi.minghao@zte.com.cn>,
	"Jie Wang" <wangjie125@huawei.com>,
	"Oleksij Rempel" <linux@rempel-privat.de>,
	"Sean Anderson" <sean.anderson@seco.com>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	"Wolfram Sang" <wsa+renesas@sang-engineering.com>,
	"Alexander Lobakin" <alexandr.lobakin@intel.com>,
	"Marco Bonelli" <marco@mebeim.net>
Subject: Re: [PATCH v3 3/5] net: Let the active time stamping layer be selectable.
Date: Fri, 10 Mar 2023 18:06:48 +0200	[thread overview]
Message-ID: <20230310160648.vwzbyood3rectlr7@skbuf> (raw)
In-Reply-To: <0d2304a9bc276a0d321629108cf8febd@walle.cc>

On Fri, Mar 10, 2023 at 02:34:07PM +0100, Michael Walle wrote:
> Yeah, but my problem right now is, that if this discussion won't find
> any good solution, the lan8814 phy timestamping will find it's way
> into an official kernel and then it is really hard to undo things.
> 
> So, I'd really prefer to *first* have a discussion how to proceed
> with the PHY timestamping and then add the lan8814 support, so
> existing boards don't show a regressions.

You don't mean LAN8814 but LAN8841, no?

For the former, PTP support was added in commit ece19502834d ("net: phy:
micrel: 1588 support for LAN8814 phy") - first present in v5.18.

For the latter, it was commit cafc3662ee3f ("net: micrel: Add PHC
support for lan8841"), and this one indeed is in the v6.3 release
candidates.

Assuming you can prove a regression, how about adding the PHY driver
whitelist *without* the lan8841 as a patch to net.git? (blaming commit
cafc3662ee3f ("net: micrel: Add PHC support for lan8841")).

Doing this will effectively deactivate lan8841 PHY timestamping without
reverting the code. Then, this PHY timestamping support could be
activated back in net-next, based on some sort of explicit UAPI call.