On Wed, Sep 18, 2013 at 10:00:31AM -0500, Grant Likely wrote: > On Wed, 18 Sep 2013 10:21:11 +0100, Florian Fainelli <f.fainelli@xxxxxxxxx> wrote: > > > > > > I understand what you're trying to do here, but it causes a troublesome > > > leakage of implementation detail into the binding, making the whole > > > thing look very odd. This binding tries to make a fixed link look > > > exactly like a real PHY even to the point of including a phandle to the > > > phy. But having a phandle to a node which is *always* a direct child of > > > the MAC node is redundant and a rather looney. Yes, doing it that way > > > makes it easy for of_phy_find_device() to be transparent for fixed link, > > > but that should *not* drive bindings, especially when that makes the > > > binding really rather weird. > > > > This is not exactly true in the sense that the "new" binding just > > re-shuffles the properties representation into something that is > > clearer and more extendible but there is not much difference in the > > semantics. > > That's not my point in the above paragraph. My point is a binding that > consists of a phandle to a node that is always a direct child is goofy > and wrong. It's not necessarily a direct child. Most of these fixed links are really ethernet switches. These are (mostly) i2c devices which are under their corresponding i2c bus node. Using a phandle from the ethernet MAC to the port of a switch not only provides the link information, but also the information to which port of the switch the MAC is connected. Another situation is that some SoCs have a MDIO bus external to the MAC and possibly shared for multiple ethernet MACs. This also requires a phandle from the MAC to the MDIO bus. So we have the situation that we need a phandle from the MAC to something that provides a link. For consistency it would be good to always use a phandle instead of having an inflexible 'fixed-link' property. You're right, the binding doesn't provide anything new, but I think it straightens things up for the future. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
