Data Sheet

Ethernet Controller I210 —Power Management
186
5.10.2.2 Conditions for Generating LTR Message with Maximum LTR Value
When LTR messaging is enabled and conditions to send a LTR message with valid bits cleared do not
exist, the I210 functions send a maximum value LTR message, with the values programmed in the
LTRMAXV register in the following cases:
1. Following a software write of 1b to the LTRC.LTR_MAX bit and the last PCIe LTR message sent had
a latency tolerance value different then the value specified in the LTRMAX register.
2. Rx EEE LPI state is detected on the Ethernet link and LTRC.EEEMS_EN is set.
3. When updated data was written to the LTRMAXV register and conditions defined instep 1. or step 2.
to send a LTR message with a maximum value exists.
When one of the previous conditions exist and the function is enabled and conditions to send a LTR
message with requirement bits cleared (See Section 5.10.2.1) doesn’t exist, the I210 sends a LTR
message with the values programmed in the LTRMAXV register.
Note: When the LTRC.LTR_MAX bit is cleared, the I210 sends a LTR message with the value placed
in the LTRMINV register, if the value is smaller than the value placed in the LTRMAXV register.
5.10.2.3 Conditions for Generating LTR Message with Minimum LTR Value
When LTR messaging is enabled, the I210’s function sends a minimum value LTR message, with the
values programmed in the LTRMINV register in the following cases:
1. Following a software write of 1b to the LTRC.LTR_MIN bit and the last PCIe LTR message sent had a
latency tolerance value different then the value specified in the LTRMINV register.
2. When updated data was written to the LTRMINV register and conditions to send a LTR message with
the requirement bits cleared (see Section 5.10.2.1) or maximum value LTR (see Section 5.10.2.2)
do not exist.
Note: If a LTR message that indicates that best possible service is requested needs to be sent, the
latency tolerance value in the LTRMINV and LTRMAXV registers should be programmed to 0x0
with the appropriate requirement bits set. In this case, the I210 sends a LTR message with
both the value and scale fields cleared to zeros.