On Fri, 2010-11-19 at 13:53 +0800, Li Yang wrote: > ><snip> > > > >> >My understanding is that the SGMII link is always at 1000Mbps speed - > >> >see figure 1 from the app note. Additionally look at figure 3. My > >> >understand from it, and the app note's text is that SGMII > >> >auto-negotiation doesn't really occur - its just passing the PHY-side > >> >auto-negotiation results to the Freescale MAC, which software then > >> >configures. I'm not sure what the purpose of the "SGMII > >> >auto-negotiation" is - its not really auto- negotiating and the same > >> >information can be read from the PHY via its MDIO interface, which is > >what is happening on X-ES boards currently. > >> > >> I guess the point is to save MDIO signals to the external PHY and read > >> the negotiated result from the internal TBI PHY. > > > >Do the P2020DS, MPC8572DS and P1/P2 RDB boards not have an MDIO interface > >to their PHYs'? I've never heard of a board that doesn't, and would guess > >the tsec driver in U-Boot requires a PHY to be accessible via MDIO to use > >the corresponding network interface. > > I'm not sure which specific silicon omits the MDIO signal. But quoting from > the app note you mentioned: > > " Depending on the PowerQUICC part used, some eTSEC’s may or may not > provide an external > MDIO management interface. However, the TBI block for each eTSEC is > associated in a one to one > manner, even if that eTSEC does not have an external MDIO connection."
I believe some parts don't have an external MDIO interface for every eTSEC. if my memory is correct the MPC8572 only has 2 MDIO ports and 3 eTSECS. But 1 MDIO port can be used to communicate with all 3 eTSECS' PHYs assuming each PHY has a unique address. (eg eTSEC1, 2, and 3 use eTSEC1's MDIO port). > The auto-negotiation mechanism between TBI PHY and real PHY does make > it possible > to save external MDIO signals if only SGMII interface is used. That seems like an awfully big sacrifice to save routing 2 signals. I've never heard of anyone doing this. I don't think the current tsec driver in U-Boot would support this configuration either, so I'm not sure how much weight it holds. > >I can forward you the email thread about SGMII auto-negotiation with > >Freescale's FAE off-list if you'd like as well. > > Yes, please. Thanks I just forwarded it. Best, Peter _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot