Re: [RFC PATCH v3 net-next 2/6] net: phylink: introduce a generic method for querying PHY in-band autoneg capability

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Antoine Tenart <atenart@kernel.org>,
	Michael Walle <michael@walle.cc>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Ioana Ciornei <ioana.ciornei@nxp.com>,
	Maxim Kochetkov <fido_max@inbox.ru>,
	Bjarni Jonasson <bjarni.jonasson@microchip.com>,
	Steen Hegelund <steen.hegelund@microchip.com>,
	"UNGLinuxDriver@microchip.com" <UNGLinuxDriver@microchip.com>,
	"bcm-kernel-feedback-list@broadcom.com" 
	<bcm-kernel-feedback-list@broadcom.com>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Claudiu Beznea <claudiu.beznea@microchip.com>
Subject: Re: [RFC PATCH v3 net-next 2/6] net: phylink: introduce a generic method for querying PHY in-band autoneg capability
Date: Thu, 23 Sep 2021 00:03:22 +0100	[thread overview]
Message-ID: <YUu2OlXElk5GR/3N@shell.armlinux.org.uk> (raw)
In-Reply-To: <20210922214827.wczsgk3yw3vjsv5w@skbuf>

On Wed, Sep 22, 2021 at 09:48:28PM +0000, Vladimir Oltean wrote:
> On Thu, Sep 23, 2021 at 12:31:16AM +0300, Vladimir Oltean wrote:
> > On Wed, Sep 22, 2021 at 10:22:19PM +0100, Russell King (Oracle) wrote:
> > > On Wed, Sep 22, 2021 at 09:14:42PM +0300, Vladimir Oltean wrote:
> > > > +static unsigned int phylink_fixup_inband_aneg(struct phylink *pl,
> > > > +					      struct phy_device *phy,
> > > > +					      unsigned int mode)
> > > > +{
> > > > +	int ret;
> > > > +
> > > > +	ret = phy_validate_inband_aneg(phy, pl->link_interface);
> > > > +	if (ret == PHY_INBAND_ANEG_UNKNOWN) {
> > > > +		phylink_dbg(pl,
> > > > +			    "PHY driver does not report in-band autoneg capability, assuming %s\n",
> > > > +			    phylink_autoneg_inband(mode) ? "true" : "false");
> > > > +
> > > > +		return mode;
> > > > +	}
> > > > +
> > > > +	if (phylink_autoneg_inband(mode) && !(ret & PHY_INBAND_ANEG_ON)) {
> > > > +		phylink_err(pl,
> > > > +			    "Requested in-band autoneg but driver does not support this, disabling it.\n");
> > > 
> > > If we add support to the BCM84881 driver to work with
> > > phy_validate_inband_aneg(), then this will always return
> > > PHY_INBAND_ANEG_OFF and never PHY_INBAND_ANEG_ON. Consequently,
> > > this will always produce this "error". It is not an error in the
> > > SFP case, but it is if firmware is misconfigured.
> > > 
> > > So, this needs better handling - we should not be issuing an error-
> > > level kernel message for something that is "normal".
> > 
> > Is this better?
> > 
> > 		phylink_printk(phy_on_sfp(phy) ? KERN_DEBUG : KERN_ERR, pl,
> > 			       "Requested in-band autoneg but driver does not support this, disabling it.\n");
> 
> Ah, not sure whether that was a trick question or not, but
> phylink_fixup_inband_aneg function does not get called for the SFP code
> path, I even noted this in the commit message but forgot:

No it wasn't a trick question. I thought you were calling
phylink_fixup_inband_aneg() from phylink_sfp_config(), but I see now
that you don't. That's what happens when you try and rush to review.

-- 
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