Extending sys/dev/mii

[Stefan Bethke]

(Now with actual patch attached. Thanks ray!)

Am 05.01.2012 um 21:52 schrieb Stefan Bethke:

> The problem with this is that the miibus instance might not be a (transitive) child of the ethernet driver that has the MII that needs to be adjusted to the new PHY settings.  And since the method does not provide any parameters about which phy or miibus did issue the method, or which ifp it applies to, bubbling it up won't work (that the scenario where the PHY for arge0 is connected to the switch's MDIO, which is attached to arge1's MDIO).
> 
>>> Since the parent will now be the mdiobus, miibus needs effectively two attachments, one to the provider of the MDIO access, the other for the ethernet interface.  I propose to associate the ethernet interface by a modified mii_attach() function that takes a device_t (of the ethernet driver) instead of the two callback function pointers.
>> 
>> Please elaborate on why these changes are technically necessary
>> to implement what you are trying do. Otherwise I prefer to avoid
>> them given the rototilling they'd cause.
> 
> Necessary is a strong word.  Right now, I'm trying to understand how a sensible change would even look like, and which combination of glue code and miibus changes make the most sense.
> 
> Let me see if I can come up with a prototype patch the next couple of days, so we don't have to theorize about the changes that might or might not be necessary.

Here's a patch that causes zero rototilling, if I'm not mistaken.

The patch implements the split between the MDIO access and notifications posted to the ethernet interface device that has the MII that needs to be adjusted in accordance with the PHY autonegotiation results.  I've added a field to the ivars struct and not the softc, because the softc is included by many network drivers, while the ivars are private to mii.c  For this reason, I believe this change is API and ABI compatible, and likely can be MFCed.  (I believe MFCing is not high on the priority list because many other parts in sys/mips would need to be MFCed first for all the Atheros platforms to become fully usable, but Adrian can correct me.)

A second patch will implement a separate MDIO bus driver, but I haven't finished that yet.  It s completely independent of the above change.


Stefan

-- 
Stefan Bethke <stb at lassitu.de>   Fon +49 151 14070811

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