Re: [PATCH net-next 3/4] net: phy: Add helper to derive the number of ports from a phy mode

From: Maxime Chevallier <maxime.chevallier@bootlin.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: davem@davemloft.net, Rob Herring <robh+dt@kernel.org>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org, thomas.petazzoni@bootlin.com,
	Florian Fainelli <f.fainelli@gmail.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	Horatiu.Vultur@microchip.com, Allan.Nielsen@microchip.com,
	UNGLinuxDriver@microchip.com
Subject: Re: [PATCH net-next 3/4] net: phy: Add helper to derive the number of ports from a phy mode
Date: Fri, 29 Jul 2022 09:32:52 +0200	[thread overview]
Message-ID: <20220729093252.50977d5c@pc-10.home> (raw)
In-Reply-To: <YuMAdACnRKsL8/xD@lunn.ch>

On Thu, 28 Jul 2022 23:32:36 +0200
Andrew Lunn <andrew@lunn.ch> wrote:

> > +int phy_interface_num_ports(phy_interface_t interface)
> > +{
> > +	switch (interface) {
> > +	case PHY_INTERFACE_MODE_NA:
> > +	case PHY_INTERFACE_MODE_INTERNAL:
> > +		return 0;  
> 
> I've not yet looked at how this is used. Returning 0 could have
> interesting effects i guess? INTERNAL clearly does have some sort of
> path between the MAC and the PHY, so i think 1 would be a better
> value. NA is less clear, it generally means Don't touch. But again,
> there still needs to be a path between the MAC and PHY, otherwise
> there would not be any to touch.
> 
> Why did you pick 0?
> 
> > +
> > +	case PHY_INTERFACE_MODE_MII:
> > +	case PHY_INTERFACE_MODE_GMII:
> > +	case PHY_INTERFACE_MODE_TBI:
> > +	case PHY_INTERFACE_MODE_REVMII:
> > +	case PHY_INTERFACE_MODE_RMII:
> > +	case PHY_INTERFACE_MODE_REVRMII:
> > +	case PHY_INTERFACE_MODE_RGMII:
> > +	case PHY_INTERFACE_MODE_RGMII_ID:
> > +	case PHY_INTERFACE_MODE_RGMII_RXID:
> > +	case PHY_INTERFACE_MODE_RGMII_TXID:
> > +	case PHY_INTERFACE_MODE_RTBI:
> > +	case PHY_INTERFACE_MODE_XGMII:
> > +	case PHY_INTERFACE_MODE_XLGMII:
> > +	case PHY_INTERFACE_MODE_MOCA:
> > +	case PHY_INTERFACE_MODE_TRGMII:
> > +	case PHY_INTERFACE_MODE_USXGMII:
> > +	case PHY_INTERFACE_MODE_SGMII:
> > +	case PHY_INTERFACE_MODE_SMII:
> > +	case PHY_INTERFACE_MODE_1000BASEX:
> > +	case PHY_INTERFACE_MODE_2500BASEX:
> > +	case PHY_INTERFACE_MODE_5GBASER:
> > +	case PHY_INTERFACE_MODE_10GBASER:
> > +	case PHY_INTERFACE_MODE_25GBASER:
> > +	case PHY_INTERFACE_MODE_10GKR:
> > +	case PHY_INTERFACE_MODE_100BASEX:
> > +	case PHY_INTERFACE_MODE_RXAUI:
> > +	case PHY_INTERFACE_MODE_XAUI:
> > +		return 1;
> > +	case PHY_INTERFACE_MODE_QSGMII:
> > +	case PHY_INTERFACE_MODE_QUSGMII:
> > +		return 4;
> > +
> > +	default:
> > +		return 0;
> > +	}
> > +}  
> 
> Have you tried without a default: ? I _think_ gcc will then warn about
> missing enum values, which will help future developers when they add
> further values to the enum.

Without the default clause, I get an error about the missing
PHY_INTERFACE_MODE_MAX case, which I don't think belongs here...

Too bad :/

> 	Andrew