XIO3130
SLLS693F–MAY 2007–REVISED JANUARY 2010
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4.2.74 Downstream Ports Link PM Latency Register
This read/write register is used to program L0s and L1 exit latencies for all XIO3130 downstream ports.
Similar information is provided in a separate register for the upstream port.
PCI register offset:
Register type:
E8h
Read/Write; Read Only
3F24h
Default value:
BIT NUMBER
RESET STATE
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 4-42. Bit Descriptions – Downstream Ports Link PM Latency Register
BIT
FIELD NAME
ACCESS
DESCRIPTION
Reserved. When read, these bits return zeros.
Endpoint L0s acceptable latency. This field is used to program the maximum acceptable
15:14
RSVD
r
latency when exiting the L0s state. This field is used to set the L0s Acceptable Latency field
in the Device Capabilities register.
000 – Less than 64 ns
001 – 64 ns up to less than 128 ns
010 – 128 ns up to less than 256 ns
011 – 256 ns up to less than 512 ns
100 – 512 ns up to less than 1 ms
101 – 1 ms up to less than 2 ms
13:11
EP_L0S_LAT
rw
110 – 2 ms to 4 ms
111 – More than 4 ms (default)
This field is loaded from EEPROM (when present) and reset with PERST.
Endpoint L1 acceptable latency. This field is used to program the maximum acceptable
latency when exiting the L1 state. This field is used to set the L1 Acceptable Latency field in
the Device Capabilities register.
000 – Less than 1 ms
001 – 1 ms up to less than 2 ms
010 – 2 ms up to less than 4 ms
10:8
EP_L1_LAT
rw
011 – 4 ms up to less than 8 ms
100 – 8 ms up to less than 16 ms
101 – 16 ms up to less than 32 ms
110 – 32 ms to 64 ms
111 – More than 64 ms (default)
This field is loaded from EEPROM (when present) and reset with PERST.
Reserved. When read, these bits return zeros.
7:6
5:3
RSVD
r
L0s exit latency. This field is used to program the maximum latency for the PHY to exit the
L0s state. This is used to set the L0s Exit Latency field in the Link Capabilities register.
000 – Less than 64 ns
001 – 64 ns up to less than 128 ns
010 – 128 ns up to less than 256 ns
011 – 256 ns up to less than 512 ns
100 – 512 ns up to less than 1 ms (default)
101 – 1 ms up to less than 2 ms
110 – 2 ms to 4 ms
L0S_EXIT_LAT
rw
111 – More than 4 ms
78
XIO3130 Configuration Register Space
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