Re: [PATCH 2/5] net: phy: hook up clause 45 autonegotiation restart

On Thu, Jun 01, 2017 at 10:16:17AM -0700, Florian Fainelli wrote:

On 06/01/2017 09:24 AM, Russell King - ARM Linux wrote:

quoted

Checking 802.3-2015, in "22.2.4 Management functions", the first
sentence requires all PHYs that respond to Clause 22 cycles to
implement BMCR and BMSR.  However, my statement about unimplemented
registers returning zero seems to be a C45 thing, not a C22 thing,
according to the C22 PICS and "45.2 MDIO Interface Registers"

However, digging a bit further, "22.2.4.2.10 Auto-Negotiation complete"
states that bit 5 shall be zero if aneg has not completed or if aneg is
unimplemented.

So how about we are more defensive than that and if we are presented
with a C45 PHY driver that does not have an aneg_done() function pointer
set we return an error/warning during driver registration?

We don't mark drivers as being C22 or C45, we rely on them matching
the IDs and/or the probe function making that decision, so it's a
tad difficult to make that decision at driver registration time.

We could reject an attempt to probe a C45 phy with a driver that
does not provide an aneg_done() pointer.

-- 
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