Re: Need help with mdiobus_register and phy

On Sat, Oct 15, 2016 at 09:39:12AM -0500, Timur Tabi wrote:

Florian Fainelli wrote:

quoted

After reading the spec again, it does not appear to me that a PHY
with PDOWN set is guaranteed or even required to respond to other
register reads such as MII_PHYID1/2, in which case we may have to
implement a MDIO bus reset routine which clears PDOWN for all PHYs
that we detect(ed), or as Andrew suggested, utilize the matching by
compatible string with the PHY OUI in it.

The 8031 does respond normally when PDOWN is set.  However, the ID
registers are not available when the SerDes bus is also powered
down. I'll call this PDOWN+.  This is a special power-down sequence
that the at803x driver does on suspend.  See my other email for
details.

So we appear to have two ways to go:

1) Take the SerDes power down out of the suspend code for the at803x.

2) Assume MII_PHYID1/2 registers are not guaranteed to be available
when the PHY is powered down. So get_phy_id should first read
MII_BMCR. If it gets 0xffff, assume there is no PHY there. If the
PDOWN bit is set, power up the PHY. Then reading the ID registers.

      Andrew