Datasheet
Datasheet, Volume 2 87
Processor Integrated I/O (IIO) Configuration Registers
3.2.4.60 LNKCON2—PCI Express* Link Control 2 Register
LNKCON2
Bus: 0 Device: 0 Function: 0 Offset: 1C0h (DMI2 MODE)
Bus: 0 Device: 0 Function: 0 Offset: C0h (PCIe* MODE)
Bus: 0 Device: 1 Function: 0–1 Offset: C0h
Bus: 0 Device: 2 Function: 0–3 Offset: C0h
Bus: 0 Device: 3 Function: 0–3 Offset: C0h
Bit Attr
Reset
Value
Description
15:13 RO 0b Reserved
12 RWS 0b
Compliance De-emphasis
This bit sets the de-emphasis level in Polling.Compliance state if the entry
occurred due to the Enter Compliance bit being 1b.
1 = -3.5 dB
0 = -6 dB
11 RWS 0b
Compliance SOS
When set to 1b, the LTSSM is required to send SKP Ordered Sets periodically in
between the (modified) compliance patterns.
10 RWS 0b
Enter Modified Compliance
When this bit is set to 1b, the device transmits Modified Compliance Pattern if the
LTSSM enters Polling.Compliance substate.
9:7 RWS-V 000b
Transmit Margin
This field controls the value of the nondeemphasized voltage level at the
Transmitter pins.
6RW-O 0b
Selectable De-emphasis
When the Link is operating at 5.0 GT/s speed, this bit selects the level of de-
emphasis for an Upstream component.Encodings:
1 = -3.5 dB
0 = -6 dB
When the Link is operating at 2.5 GT/s speed, the setting of this bit has no effect.
5RWS0b
Hardware Autonomous Speed Disable
When set, this bit disables hardware from changing the Link speed for device
specific reasons other than attempting to correct unreliable Link operation by
reducing Link speed.
4RWS-V0b
Enter Compliance
Software is permitted to force a link to enter Compliance mode at the speed
indicated in the Target Link Speed field by setting this bit to 1b in both
components on a link and then initiating a hot reset on the link.
3:0 RWS-V 2h
Target Link Speed
This field sets an upper limit on link operational speed by restricting the values
advertised by the upstream component in its training sequences. Defined
encodings are:
0001b = 2.5 Gb/s Target Link Speed
0010b = 5 Gb/s Target Link Speed
All other encodings are reserved.
If a value is written to this field that does not correspond to a speed included in
the Supported Link Speeds field, IIO will default to Gen1 speed.
This field is also used to set the target compliance mode speed when software is
using the Enter Compliance bit to force a link into compliance mode.