svn commit: r227687 - head/sys/dev/mii

[John Baldwin]

On Friday, November 18, 2011 5:39:46 pm Marius Strobl wrote:
> Author: marius
> Date: Fri Nov 18 22:39:46 2011
> New Revision: 227687
> URL: http://svn.freebsd.org/changeset/base/227687
> 
> Log:
>   - Add a hint.miibus.X.phymask hint, allowing do individually exclude PHY
>     addresses from being probed and attaching something including ukphy(4)
>     to it. This is mainly necessarily for PHY switches that create duplicate
>     or fake PHYs on the bus that can corrupt the PHY state when accessed or
>     simply cause problems when ukphy(4) isolates the additional instances.
>   - Change miibus(4) to be a hinted bus, allowing to add child devices via
>     hints and to set their attach arguments (including for automatically
>     probed PHYs). This is mainly needed for PHY switches that violate IEEE
>     802.3 and don't even implement the basic register set so we can't probe
>     them automatically. However, the ability to alter the attach arguments
>     for automatically probed PHYs is also useful as for example it allows
>     to test (or tell a user to test) new variant of a PHY with a specific
>     driver by letting an existing driver attach to it via manipulating the
>     IDs without the need to touch the source code or to limit a Gigabit
>     Ethernet PHY to only announce up to Fast Ethernet in order to save
>     energy  by limiting the capability mask. Generally, a driver has to
>     be hinted via hint.phydrv.X.at="miibusY" and hint.phydrv.X.phyno="Z"
>     (which already is sufficient to add phydrvX at miibusY at PHY address
>     Z). Then optionally the following attach arguments additionally can
>     be configured:
>     hint.phydrv.X.id1
>     hint.phydrv.X.id2
>     hint.phydrv.X.capmask
>   - Some minor cleanup.

I was looking at this today with bz to try to figure out how to use this.
It strikes me that in a case of a bus with devices that have IDs it can
be useful to not hardcode the driver name and unit number, but to be able
to create a device and let the normal driver probe mechanics work.  The
existing miibus_hinted_child() routine already largely enforces that by
ensuring that any new child has a unique phyno address.  Two approaches I
can think of are:

1) Never hardcode the name and unit number.

2) Don't hardcode the name and unit number if the name is "phy".

This would let you do something like:

hint.phy.0.at="miibus0"
hint.phy.0.phyno="1"
hint.phy.0.id1="xxx"
hint.phy.0.id2="yyy"

And then 'e1000phy' or 'brphy' or whoever could manage the phy.  Though 
perhaps in the case of hinted children you want to always force the phy 
driver?

-- 
John Baldwin