10Ehci Caching; 12Function Level Reset Support (Flr); 1Flr Steps; Usb Pre-Fetch Based Pause - Intel 6 SERIES CHIPSET - DATASHEET 01-2011 Datasheet

Determining Debug Peripheral Presence
After enabling the debug port functionality, debug software can determine if a debug
peripheral is attached by attempting to send data to the debug peripheral. If all
attempts result in an error (Exception bits in the Debug Port Control/Status register
indicates a Transaction Error), then the attached device is not a debug peripheral. If the
debug port peripheral is not present, then debug software may choose to terminate or
it may choose to wait until a debug peripheral is connected.
5.18.10 EHCI Caching
EHCI Caching is a power management feature in the USB (EHCI) host controllers which
enables the controller to execute the schedules entirely in cache and eliminates the
need for the DMA engine to access memory when the schedule is idle. EHCI caching
allows the processor to maintain longer C-state residency times and provides
substantial system power savings.
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5.18.11 Intel
The Intel USB Pre-Fetch Based Pause is a power management feature in USB (EHCI)
host controllers to ensure maximum C3/C4 processor power state time with C2 popup.
This feature applies to the period schedule, and works by allowing the DMA engine to
identify periods of idleness and preventing the DMA engine from accessing memory
when the periodic schedule is idle. Typically in the presence of periodic devices with
multiple millisecond poll periods, the periodic schedule will be idle for several frames
between polls.
The Intel USB Pre-Fetch Based Pause feature is disabled by setting bit 4 of EHCI
Configuration Register
5.18.12 Function Level Reset Support (FLR)
The USB EHCI Controllers support the Function Level Reset (FLR) capability. The FLR
capability can be used in conjunction with Intel
an Operating System in a Virtual Machine to have complete control over a device,
including its initialization, without interfering with the rest of the platform. The device
provides a software interface that enables the Operating System to reset the whole
device as if a PCI reset was asserted.
5.18.12.1 FLR Steps
5.18.12.1.1 FLR Initialization
1. A FLR is initiated by software writing a '1' to the Initiate FLR bit.
2. All subsequent requests targeting the Function will not be claimed and will be
Master Abort Immediate on the bus. This includes any configuration, I/O or
Memory cycles, however, the Function shall continue to accept completions
targeting the Function.
5.18.12.1.2 FLR Operation
The Function will Reset all configuration, I/O and memory registers of the Function
except those indicated otherwise and reset all internal states of the Function to the
default or initial condition.
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USB Pre-Fetch Based Pause

Section 16.2.1.
Functional Description
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Virtualization Technology. FLR allows
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