Data Sheet
Interconnects—Ethernet Controller I210
37
3.1.3.1.2.2 Case 2 - DCA Enabled in the System, but Disabled for the Request
• Legacy DCA platforms - If DCA is disabled for the request, the tags allocation is identical to the case
where DCA is disabled in the system. Refer to Table 3-2.
• DCA 1.0 platforms - All write requests have a tag value of 0x00.
Note: When in DCA 1.0 mode, messages and MSI/MSI-X write requests are sent with the no-hint
tag.
3.1.3.1.2.3 Case 3 - DCA Enabled in the System, DCA Enabled for the Request
• Legacy DCA platforms: the request tag is constructed as follows:
— Bit[0] – DCA Enable
— Bits[3:1] - The CPU ID field taken from the CPUID[2:0] bits of the RXCTL or TXCTL registers
— Bits[7:4] - Reserved
• DCA 1.0 platforms: the request tag (all 8 bits) is taken from the CPUID field of the RXCTL or TXCTL
registers
3.1.3.1.2.4 Case 4 - TPH Enabled in the System, TPH Enabled for the Request
• The request tag (all 8 bits) is taken from the CPUID field of the adequate register or context as
listed in Table 7-61.
3.1.3.2 Completion Timeout Mechanism
In any split transaction protocol, there is a risk associated with the failure of a requester to receive an
expected completion. To enable requesters to attempt recovery from this situation in a standard
manner, the completion timeout mechanism is defined.
The completion timeout mechanism is activated for each request that requires one or more completions
when the request is transmitted. The I210 provides a programmable range for the completion timeout,
as well as the ability to disable the completion timeout altogether. The completion timeout is
programmed through an extension of the PCIe capability structure (refer to Section 9.4.6.12).
The I210’s reaction in case of a completion timeout is listed in Table 3-12.
The I210 controls the following aspects of completion timeout:
Table 3-2. IDs in Write Transactions (DCA Disabled Mode)
Tag ID Description
0x0 - 0x1 Reserved
0x2 Tx descriptors write-back / Tx head write-back
0x3 Reserved
0x4 Rx descriptors write-back
0x5 Reserved
0x6 Write data
0x7 - 0x1D Reserved
0x1E MSI and MSI-X
0x1F Reserved