Data Sheet

Ethernet Controller I210 —Initialization
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•If needed, set TDWBAL/TWDBAH to enable head write back.
• Enable the queue using TXDCTL.ENABLE (queue zero is enabled by default).
• Poll the TXDCTL register until the ENABLE bit is set.
Note: The tail register of the queue (TDT[n]) should not be bumped until the queue is enabled.
Enable transmit path by setting TCTL.EN. This should be done only after all other settings are done.
4.5.10.1 Dynamic Queue Enabling and Disabling
Transmit queues can be dynamically enabled or disabled given the following procedure is followed:
Enabling:
• Follow the per queue initialization described in the previous section.
Disabling:
• Stop storing packets for transmission in this queue.
• Wait until the head of the queue (TDH) is equal to the tail (TDT); the queue is empty.
• Disable the queue by clearing TXDCTL.ENABLE.
The Tx path might be disabled only after all Tx queues are disabled.
4.5.11 Alternate MAC Address Support
In some systems, the MAC address used by a port needs to be replaced with a temporary MAC address
in a way that is transparent to the software layer. One possible usage is in blade systems, to enable a
standby blade to use the MAC address of another blade that failed, so that the network image of the
entire blade system does not change.
In order to enable this mode, a management console might change the MAC address in the Flash
image. It is important in this case to be able to keep the original MAC address of the device as
programmed at the factory.
In order to support this mode, the I210 provides the Alternate Ethernet MAC Address Flash structure to
store the original MAC address. This structure is described in Section 6.8.8. When the MAC address is
changed, the port factory MAC address should be written to the Alternate Ethernet MAC Address
structure before writing the new Ethernet MAC address to the ports Ethernet Address Flash words (refer
to Section 6.2.1).
In some systems, it might be advantageous to restore the original MAC address at power on reset, to
avoid conflicts where two network controllers would have the same MAC address. At power up, the I210
restores the LAN MAC addresses stored in the Alternate Ethernet MAC Address Flash structure to the
regular Ethernet MAC address Flash words (refer to Section 6.2.1) if the following conditions are met:
1. The restore MAC address bit in the Common Firmware Parameters Flash word is set
(Section 6.7.1.2).
2. The value in word 0x37 (Section 6.8.8) is not 0xFFFF.
3. The MAC address set in the regular Ethernet MAC Address Flash words is different than the address
stored in the Alternate Ethernet MAC address Flash structure.
4. The address stored in the alternate Ethernet MAC address structure is valid (not all zeros or all
ones).