Data Sheet

Programming Interface — Ethernet Controller I210
545
8.25.9 Latency Tolerance Reporting (LTR) Minimum Values - LTRMINV
(0x5BB0; R/W)
Field Bit(s) Initial Value Description
LTRV 9:0 0x5
Latency Tolerance Value.
This field indicates the latency tolerance supported when conditions for minimum
latency tolerance exist (Refer to Section 5.11.2.1).
LTRV values are multiplied by 32,768 ns or 1,024 ns depending on the Scale field, to
indicate latency tolerance supported in nanoseconds. A value of 0 indicates that the
device is impacted by any delay and that best possible service is requested.
The I210 reports the same value for both snoop and no snoop requirements. If no
memory latency requirement exists for either snoop or no snoop accesses, the
appropriate Requirement bit is cleared.
Note: Software should subtract time required to move from L1 to L0 from LTR value.
Scale 12:10 011b
Latency Scale.
This field provides a scale for the value contained within the LTRMINV.LTRV field.
Encoding:
010b = LTRV value times 1,024 ns.
011b = LTRV value times 32,768 ns.
Others = Reserved.
Reserved 14:13 0x0
Reserved.
Write 0x0, ignore on read.
LSNP
Requirement
15 0b
LTR Snoop Requirement.
0b = No latency requirements in snoop memory access.
1b = Latency tolerance in snoop memory access specified in LTRMINV.LTRV field.
Reserved 30:16 0x0
Reserved.
Write 0x0, ignore on read.
LNSNP
Requirement
31 0b
LTR Non-snoop Requirement.
0b = No latency requirements in non-snoop memory access.
1b = Latency tolerance in non-snoop memory access specified in LTRMINV.LTRV field.