Teledyne LeCroy Summit Z3-16 PCI Express Multi-lane Exerciser User Manual - Manual (Page 35)

Summit Z3‐16 PCI Express Multi‐Lane Exerciser User Manual 35
LTSSM Control Teledyne LeCroy
4.2.1 Link Speed Control
The Summit Z3‐16 Exerciser supports traffic generation at three speeds: 2.5, 5.0 and 8.0
GT/s. The link speed control shows the current link speed and has buttons to initiate
speed switches to corresponding speeds.
When you press a speed control button, the Summit Z3‐16 Exerciser initiates a speed
switch for the speed indicated on that button. The link may not change speed if the speed
switch operation is unsuccessful.
The speed switch buttons may be enabled/disabled based on the speed configuration
settings in the exerciser’s Generation Options settings. For example, if you set up a
Summit Z3‐16 Exerciser as a Gen2 capable device in the Generation Options, the Gen3
(8.0GT/s) speed switch button will be disabled.
4.2.2 Link Width Control
The Summit Z3‐16 Exerciser supports traffic generation at five different link widths: x1, x2
x4, x8 and x16. The link width control shows the current link width and has buttons to
initiate link width changes to corresponding widths.
When you press a link width control button, the Summit Z3‐16 Exerciser will initiate a link
width change for the link width indicated on that button. The link width after the
operation may not match the desired link width if the operation is unsuccessful.
The link width buttons may be enabled/disabled based on the link width configuration
settings in the exerciser’s Generation Options settings. For example, if you set up the
Summit Z3‐16 as a x4 device in the Generation Options, the x8 and x16 link width change
buttons are disabled.
4.2.3 Link State Control
The Summit Z3 Exerciser currently supports direction to the following nine link states:
Detect, Recovery, Hot Reset, Disabled, L0, L0S, Loopback (Compliance Rx=0), Loopback
(Compliance Rx=1), Clear Loopback, Direct to L1 (Device Emulation mode only) and Direct
to L2 (Device Emulation mode only). The link state control shows the current state of the
PCI Express Link. For example, when the Link is down, it shows Detect.
You can direct the Summit Z3‐16 into one of the stated nine specific LTSSM states by
selecting the desired state in the “Go to Link State” drop down box and pressing the Apply
button. The exerciser will then receive instructions to transition into the selected state.
The resulting link state after such a transition may be different than the selected state
based on the link. For example, if you direct the Summit Z3‐16 LTSSM into a Recovery
state when the link is at L0, the Summit Z3‐16 will initiate a recovery sequence, but after
the recovery the link should get back to the L0 state.
The intermediate link states, such as Polling and Configuration, are handled by the
Summit Z3‐16 exerciser. After receiving a link transition command to L0 / connect, the
LTSSM is alive, the exerciser will keep the Link active just as any other PCI Express device
would, this includes handling of the Recovery states and subsequent retraining events.