> > > > > SGMII uses the same coding as 1000base-x, but the latter works > > > > > only with one speed (1000mbps), while the former can also work > > > > > in 10mbps and 100mbps (by repeating each byte 100 or 10 times, > respectively). > > > > > > > > > > Then there is 2500base-x, which is the same as 1000base-x, but > > > > > with the clock being at 2.5x the speed of 1000base-x clock. > > > > > > > > > > But there is no analogue of the SGMII protocol (i.e. the > > > > > repearing of bytes in order to achieve lower speed) for the 2500base- > x. > > > > > > > > > > So what I am confused about here is what is supposed to be the > > > > > difference between > > > > > PHY_INTERFACE_MODE_SGMII_2500 > > > > > and > > > > > PHY_INTERFACE_MODE_2500BASEX > > > > > ? > > > > > > > > > > Marek > > > > > > I not sure what is correct naming for these mode. PHY_INTERFACE > > > includes both MAC2PHY interfaces(MII, RGMII and etc), PHY2PHY > > > interfaces(like > > > BASEX) and SGMII(which is kind of both). > > > For both 2500BASEX and SGMII_2500 Serdes lanes set to HS-SGMII in > > > 3.125G speed, but MAC configured differently and autoneg cannot be > supported. > > > > > > Regards, > > > Stefan. > > > > Since we already has PHY_INTERFACE_MODE_SGMII and > > PHY_INTERFACE_MODE_QSGMII (5G mode), maybe we should call > PHY_INTERFACE_MODE_HSGMII - High-Serial Gigabit Media Independent > Interface (HSGMII, 3.125Gbps). > > And we have now autonegotiation in this discussion. Just today I sent a > question to Marvell about 2500base-x and why inband autonegotiation is not > supported there, while it is for 1000base-x.
To clear thing out, inband autonegotiation is negotiation of pause, speed and duplex over PCS(usually between MAC and PHY). > So are you saying that 2500base-x mode is like 1000base-x, but at 2.5g speed, > and without inband autonegotiation? >From Serdes configurations point of view - lanes configured to 3_125G in >2500base-x and to 1_25G in 1000base-x. MAC doesn't support inband autonegotiation in base-x mode. PHY side still can negotiate pause. So: Host side doesn't support inband autoneg(speed/duplex) and speed/duplex fixed. Line side can support autoneg of pause. > And meanwhile HS-SGMII mode is like SGMII, but at 2.5g speed, and _WITH_ > autonegotiation? And what does this autonegotiation support? SGMII has inband negotiation of speed and duplex(1000/100/10 - full/half), but since serdes reconfiguration required to switch between HS-SGMII and SGMII. inband negotiation between 2.5C and 1G not supported. So for example if you have: MAC/Serdes set to 2.5G <-> PHY that support negotiation of link and negotiated 1G speed with link partner. Packet processor driver should reconfigure Serdes Lanes speed. > Does is support only negotiation of Pause? Or does it support negotiation of > link > duplexicity and speed as well? In HS-SGMII there no much options speed always 2500 and duplex full, only pause taken from PCS inband Auto-Negotiation. For SGMII pause, duplexicity and speed negotiation supported. Stefan, Regards.
