Flexible Port Width Configuration
The lane width for each port can be individually configured
through auto-negotiation, hardware strapping, upstream
software configuration, or through an optional EEPROM.
The PEX 8524 supports a large number of port configurations.
For example, if you are using the PEX 8524 in a fan-out
application, you may configure the upstream port as x8 and
the downstream ports as four x4 ports; two x8 ports for dual-
graphics fan-out; or other combinations, as long as you don’t
run out of lanes (24) or ports (6). In a peer-to-peer application
you can configure all six ports as x4. Figure 1 shows the most
common port configurations.
SerDes Power and Signal Management
The ExpressLane PEX 8524 supports
software control
of the
SerDes outputs
to allow optimization of power
and signal strength in a system. The PLX SerDes
implementation supports four levels of power – off, low,
typical, and high. The SerDes block also supports
loop-back
modes
and
advanced reporting of error conditions,
which
enables efficient debug and management of the entire system.
Flexible Virtual Channel Arbitration
The ExpressLane PEX 8524 switches support
hardware fixed
and Round Robin arbitration schemes
for two virtual
channels on each port. This allows for the fine tuning of
Quality of Service for efficient use of packet buffers and
system bandwidth.
Applications
Suitable for
host-centric
as well as
peer-to-peer traffic
patterns,
the PEX 8524 can be configured for a wide variety
of form factors and applications.
Host-Centric Fan-out
The PEX 8524, with its symmetric or asymmetric lane
configuration capability, allows user specific tuning to a
variety of host-centric applications.
Figure 1. Common Port Configurations
Hot Plug for High Availability
Hot plug capability allows users to replace hardware modules
and perform maintenance without powering down the system.
The PEX 8524 hot plug capability and
Advanced Error
Reporting
features makes it suitable for
High Availability
(HA) applications.
Each downstream port includes a Standard
Hot Plug Controller. If the PEX 8524 is used in an application
where one or more of its downstream ports connect to PCI
Express slots, each port’s Hot Plug Controller can be used to
manage the hot-plug event of its associated slot. Furthermore,
its upstream port is a
hot-plug client,
allowing it to be
used
on hot-pluggable adapter cards, backplanes, and fabric
modules.
Figure 2. Fan-in/out Usage
Figure 2 shows a typical
server-based
design, where the root
complex provides a PCI Express link that needs to be fanned
into a larger number of smaller ports for a variety of I/O
functions, each with different bandwidth requirements.
In this example, the PEX 8524 would typically have an 8-lane
upstream port, and as many as 5 downstream ports (4 shown
here). The downstream ports can be of differing widths if
required. The figure also shows how some of the ports can be
bridged to provide
PCI or PCI-X
slots through the use of the
ExpressLane
PEX 8114 and PEX 8111 PCIe
bridging
devices.
Fully Compliant Power Management
For applications that require power management, the PEX
8524 device supports both link (L0, L0s, L1, L2/L3 Ready,
and L3) and device (D0 and D3hot) power management states,
in compliance with the PCI Express power management
specification.
PLX [ PLX TECHNOLOGY ]
