Re: [PATCH RFC net-next 5/5] net: dsa: always use phylink for CPU and DSA ports

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: "Andrew Lunn" <andrew@lunn.ch>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	"Alvin __ipraga" <alsi@bang-olufsen.dk>,
	"Claudiu Manoil" <claudiu.manoil@nxp.com>,
	"David S. Miller" <davem@davemloft.net>,
	"DENG Qingfang" <dqfext@gmail.com>,
	"Eric Dumazet" <edumazet@google.com>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"George McCollister" <george.mccollister@gmail.com>,
	"Hauke Mehrtens" <hauke@hauke-m.de>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Kurt Kanzenbach" <kurt@linutronix.de>,
	"Landen Chao" <Landen.Chao@mediatek.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	netdev@vger.kernel.org, "Paolo Abeni" <pabeni@redhat.com>,
	"Sean Wang" <sean.wang@mediatek.com>,
	UNGLinuxDriver@microchip.com,
	"Vivien Didelot" <vivien.didelot@gmail.com>,
	"Woojung Huh" <woojung.huh@microchip.com>,
	"Marek Behún" <kabel@kernel.org>
Subject: Re: [PATCH RFC net-next 5/5] net: dsa: always use phylink for CPU and DSA ports
Date: Thu, 7 Jul 2022 11:09:43 +0100	[thread overview]
Message-ID: <Ysaw56lKTtKMh84b@shell.armlinux.org.uk> (raw)
In-Reply-To: <YsW3KSeeQBiWQOz/@shell.armlinux.org.uk>

On Wed, Jul 06, 2022 at 05:24:09PM +0100, Russell King (Oracle) wrote:
> On Wed, Jul 06, 2022 at 01:26:21PM +0300, Vladimir Oltean wrote:
> > Can we please limit phylink_set_max_link_speed() to just the CPU ports
> > where a fixed-link property is also missing, not just a phy-handle?
> > Although to be entirely correct, we can also have MLO_AN_INBAND, which
> > wouldn't be covered by these 2 checks and would still represent a valid
> > DT binding.
> 
> phylink_set_max_fixed_link() already excludes itself:
> 
>         if (pl->cfg_link_an_mode != MLO_AN_PHY || pl->phydev || pl->sfp_bus)
>                 return -EBUSY;
> 
> intentionally so that if there is anything specified for the port, be
> that a fixed link or in-band, then phylink_set_max_fixed_link() errors
> out with -EBUSY.
> 
> The only case that it can't detect is if there is a PHY that may be
> added to phylink at a later time, and that is what the check above
> is for.

I've updated the function description to mention this detail:

+/**
+ * phylink_set_max_fixed_link() - set a fixed link configuration for phylink
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * Set a maximum speed fixed-link configuration for the chosen interface mode
+ * and MAC capabilities for the phylink instance if the instance has not
+ * already been configured with a SFP, fixed link, or in-band AN mode. If the
+ * interface mode is PHY_INTERFACE_MODE_NA, then search the supported
+ * interfaces bitmap for the first interface that gives the fastest supported
+ * speed.

Does this address your concern?

Thanks.

-- 
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