[vortex] 3C905TX doesn't see 10Mbps hub till unplugged/replugged

[Donald Becker]

Summary: read
  http://www.scyld.com/diag/mii-status.html


On Fri, 30 Jun 2000, Bogdan Costescu wrote:

> On Mon, 26 Jun 2000, Donald Becker wrote:
> > This might break the very next chip revision.  If we keep to standard MII
> > behavior, rather than rely on additional features, we have a better chance
> > of continuing to work.
...
> - register 5 (lkpar) which shows what are the capabilities of the remote
> end. When this is 0, something is wrong!
> AFAIK, these are standard MII registers, so they should be available on
> all cards.

The standard doesn't define the contents of MII reg 5 when autonegotiation
hasn't occurred.  Some transceivers report the link speed without setting
the 0x4000 "autonegotiation complete" bit, but others just leave reg 5 set
to '0x0000'.

This information is at
  http://www.scyld.com/diag/mii-status.html
but perhaps it's not clear that reporting the link speed in MII reg 5 is
convenience feature that goes beyond the standard.

> - register 1 (bmsr and new_bmsr). The condition
> 	(bmsr & 0x0016) == 0x0004 is true when the link is established,
> false otherwise.

Keep in mind that these are all "sticky" bits.  You have have to read the
register a second time to get the current values.  Also, in some cases
you'll see a working link with the Tx jabber bit set.


Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Beowulf Clusters / Linux Installations
Annapolis MD 21403