[PATCH 6/6] net/phy: Expose 100base-T capability only

[Benjamin Herrenschmidt]

On Thu, 2016-05-05 at 22:55 +0930, Joel Stanley wrote:
> On Thu, May 5, 2016 at 10:57 AM, Cyril Bur <cyrilbur at gmail.com>
> wrote:
> > 
> > From: Gavin Shan <gwshan at linux.vnet.ibm.com>
> > 
> > I don't know the specific PHY model deployed on Firestone BMC, but
> > currently used one (PHY_ID_BCM54210E) isn't correct. BCM54210E
> > supports 1000base-T but the PHY on Firestone BMC shouldn't support
> > that mode as uboot uses 100base-T mode.
> > 
> > When exposing 1000base-T capability, the MAC is forced to have the
> > same mode though the PHY is working in 100base-T mode in fact. It
> > causes the mode mismatch between PHY/MAC and the ethernet network
> > doesn't work.
> > 
> > It's a temporary fix. After the PHY model is confirmed, we need
> > to enable the correct PHY driver instead current one for BCM54210E.
> > 
> > Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
> > 
> > [Cyril]
> > The plot thickens, it does appear that this IS the correct PHY on
> > firestones. This patch is definitely required for networking to be
> > functional though.
> We should get someone in Austin to boot a firestone without this
> patch
> and see what it does. You shouldn't need a pdu as long as you get it
> right the first time :)

The MAC in the ast2400 is a gigabit MAC. So it should all work normally
at 1000bT. If not, then something is wrong that needs to be
investigated:

	- Either the interface between MAC and PHY isn't wired
correctly (RGMII vs. RMII, RGMII uses more pins and a diff. clock)

	- Or we don't set a setting or strap somewhere to switch
between those modes (hardware strapping bit[7:6], SCU[A0], ...)

	- Both ?

If we are indeed limited to 100bT, then we should expose that one way
or another in the device-tree in order to limit the advertized speed in
the PHY driver.

Cheers,
Ben.