On Tue, 2009-11-03 at 17:52 -0600, Peter Tyser wrote:
In SGMII mode the link between a processor's internal TBI PHY and an external PHY should always be 1000Mbps, full duplex. Also, the SGMII interface between an internal TBI PHY and external PHY does not support in-band auto-negotation.
Previously, when configured for SGMII mode a TBI PHY would attempt to restart auto-negotation during initializtion. This auto-negotation between a TBI PHY and external PHY would fail and result in unusable ethernet operation.
Forcing the TBI PHY and and external PHY to link at 1000Mbps full duplex in SGMII mode resolves this issue of auto-negotation failing.
Note that 10Mbps and 100Mbps operation is still possible on the external side of the external PHY even when SGMII is operating at 1000Mbps. The SGMII interface still operates at 1000Mbps, but each byte of data is repeated 100 or 10 times for 10/100Mbps and the external PHY handles converting this data stream into proper 10/100Mbps signalling.
Signed-off-by: Peter Tyser ptyser@xes-inc.com
In-band SGMII auto-negotiation doesn't work according to a lengthy discussion with a Freescale FAE and the AN3869 SGMII appnote. XES's MPC8572 and MPC8640 boards need this patch in order to use ethernet. These boards generally use SGMII to connect to an BCM5482S PHY which has an external gigabit-capable copper or fiber interface.
I meant to say "XES's MPC8572 boards need this patch in order to use ethernet, and I assume our future 4080-based boards will too." This change shouldn't have any impact on 8640-based boards.
Peter