AXI Bridge for PCI Express v2.4
33
PG055 June 4, 2014
Chapter 2:
Product Specification
PHY Status/Control Register (Offset 0x144)
The PHY Status/Control register (described in
) provides the status of the current
PHY state, as well as control of speed and rate switching for Gen2-capable cores.
Table 2-15:
PHY Status/Control Register
Bits
Name
Core
Access
Reset
Value
Description
0
Link Rate
RO
0
Reports the current link rate. 0b = 2.5 GT/s, 1b = 5.0 GT/s.
2:1
Link Width
RO
0
Reports the current link width. 00b = x1, 01b = x2, 10b = x4, 11b
= x8.
8:3
LTSSM State
RO
0
Reports the current Link Training and Status State Machine
(LTSSM) state. Encoding is specific to the underlying integrated
block.
10:9
Lane Reversal
RO
0
Reports the current lane reversal mode.
• 00b: No reversal
• 01b: Lanes 1:0 reversed
• 10b: Lanes 3:0 reversed
• 11b: Lanes 7:0 reversed
11
Link Up
RO
0
Reports the current PHY Link-up state.
• 1b: Link up
• 0b: Link down
Link up indicates the core has achieved link up status, meaning
the LTSSM is in the L0 state and the core can send/receive data
packets.
15:12 Reserved
RO
0
Reserved
17:16 Directed Link
Width
RW
0
Specifies completer link width for a directed link change
operation. Only acted on when Directed Link Change specifies a
width change.
• 00b: x1
• 01b: x2
• 10b: x4
• 11b: x8
18
Directed Link
Speed
RW
0
Specifies completer link speed for a directed link change
operation. Only acted on when Directed Link Change specifies a
speed change.
• 0b: 2.5 GT/s
• 1b: 5.0 GT/s
19
Directed Link
Autonomous
RW
0
Specifies link reliability or autonomous for directed link change
operation.
• 0b: Link reliability
• 1b: Autonomous