82801DB Datasheet, PDF (202/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

Functional Description
5.17.7.4
ACPI System States
The EHC behavior as it relates to other power management states in the system is summarized in
the following list:
• The System is always in the S0 state when the EHC is in the D0 state. However, when the
EHC is in the D3 state, the system may be in any power management state (including S0).
• When in D0, the Pause feature (See Section 5.17.7.1) enables dynamic processor low-power
states to be entered.
• The PLL in the EHC is disabled when entering the S3/S4/S5 states (core power turns off).
• All core well logic is reset in the S3/S4/S5 states (core power turns off).
5.17.8 Interaction with Classic Host Controllers
The EHC shares the six USB ports with three UHCI Host controllers in the ICH4. The USB UHCI
controller at D29:F0 shares ports 0 and 1; the USB UHCI controller at D29:F1 shares ports 2 and 3;
and the USB UHCI controller at D29:F2 shares ports 4 and 5 with the EHCI controller. There is
very little interaction between the USB EHCI and the USB UHCI controllers other than the muxing
control which is provided as part of the EHCI controller.
Figure 5-19 depicts the USB Port Connections at a conceptual level. The dashed rectangle
indicates all of the logic that is part of the EHC cluster.
Figure 5-19. Intel^® ICH4 USB Port Connections
Port 5
Port 4
Port 3
Port 2
Port 1
Port 0
UHCI #3
(D29:F2)
UHCI #2
(D29:F1)
UHCI #1
(D29:F0)
Debug
Port
EHCI (D29:F7)
5.17.8.1
Port-Routing Logic
Integrated into the EHC functionality is port-routing logic, which performs the muxing between the
USB UHCI and USB EHCI host controllers. The ICH4 conceptually implements this logic as
described in Section 4.2 of the Enhanced Host Controller Interface (EHCI) for Universal Serial
Bus Specification. If a device is connected that is not capable of USB 2.0’s high-speed signaling
protocol or if the EHCI software drivers are not present as indicated by the Configured Flag, then
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Intel^® 82801DB ICH4 Datasheet