P1010/P1014 Ethernet (eTSEC) Specific FAQs

[#1]

Section 4.4.3.11 in Reference Manual states, "Note that if SGMII mode is not selected on eTSEC1, then it is configured to be in RGMII mode." Yet the MAC is coming up disabled, not RGMII. How can I configure eTSEC1 in RGMII mode in this case?

It is not possible to configure eTSEC1 in RGMII mode once it's configured in SGMII mode via POR configs.

TSEC1 MAC appears to be disabled when set to mode "11" Table 4-19. Looking at the Table 15-17, it appears if I have them set ECNTRL fields and MACCFG2[I/F] fields for interface mode RGMII, with cfg_io_ports[0:1] = 11, then that should set TSEC1 to RGMII properly, with 2 independant PCIe X1 ports on SerDes SD2. Is that correct?

DEVDISR[TSEC1] is 0 at reset. DEVDISR[TSEC2] = n => if PCIe is configured as x4 or SERDES is disabled, DEVDISR[TSEC2] will be disabled. DEVDISR[TSEC3]= n => if TSEC1 is used in MII, TSEC3 can be used only in SGMII. if PCIe is configured as x4 or SERDES is disabled, DEVDISR[TSEC3] = 1.

Which P1010 TBI PHY register bit(s) should be used to determine SGMII link status? Is this the Remote Fault and Link Status bits of the P1010 TBI Status Register (SR) which is documented in section 15.5.4.1.2 of the P1010 Reference Manual? 

Yes, this is the register (SR) which indicates link status and the above mentioned bits (Link Status/Remote Fault) are used to determine SGMII link status. The meaning of Remote Fault flag is that the PHY is not hearing (code group alignment is lost) the local end (MAC) and is sending this alarm towards the local end in hope the opposite direction works. This flag indicates unstable communication. Try reading it several times since each read clears it. If it reappears, there is something really wrong or misconfigured. The PHY normally shouldn't propagate this flag from the cable side, but check with its' documentation for the case. Read the PHY status through the management interface (MDIO) to check the status of the external link (the MIIMSTAT register).

How does the P1010 TBI PHY register access work? Is only the local TBI PHY accessible from a given eTSEC's MDIO register interface or does assigning all TBI PHYs the same address result in collisions?

P1010 TBI PHY register are read and written through the eTSEC MDIO registers just like external PHY registers. The address of each TBI PHY is set in the memory mapped TBIPA—TBI PHY address register. The uBoot TSEC device driver assigns the address 0x1f to all three TBI PHYs in the P1010 in their respective TBIPA registers. For the internal TBI block this is controlled by the TBIPA register for each eTSEC block. The reset value of this register is 0x0, which is not a valid PHY address. Therefore this register must be initialized for each TBI (thus SGMII) port in the system. For external PHY devices the address is typically a pin strapping option, so the designer must ensure that the PHY addresses of the external phys are different from any internal TBI that may be sharing that management interface.