82801FB Datasheet, PDF (207/786 Pages) Intel Corporation – Intel I/O Controller Hub 6 (ICH6) Family

Functional Description
5.20.8.2
5.20.8.3
Device Connects
The Enhanced Host Controller Interface Specification for Universal Serial Bus, Revision 1.0
describes the details of handling Device Connects in Section 4.2. There are four general scenarios
that are summarized below.
1. Configure Flag = 0 and a full-speed/low-speed-only Device is connected
— In this case, the UHC is the owner of the port both before and after the connect occurs.
The EHC (except for the port-routing logic) never sees the connect occur. The UHCI
driver handles the connection and initialization process.
2. Configure Flag = 0 and a high-speed-capable Device is connected
— In this case, the UHC is the owner of the port both before and after the connect occurs.
The EHC (except for the port-routing logic) never sees the connect occur. The UHCI
driver handles the connection and initialization process. Since the UHC does not perform
the high-speed chirp handshake, the device operates in compatible mode.
3. Configure Flag = 1 and a full-speed/low-speed-only Device is connected
— In this case, the EHC is the owner of the port before the connect occurs. The EHCI driver
handles the connection and performs the port reset. After the reset process completes, the
EHC hardware has cleared (not set) the Port Enable bit in the EHC’s PORTSC register.
The EHCI driver then writes a 1 to the Port Owner bit in the same register, causing the
UHC to see a connect event and the EHC to see an “electrical” disconnect event. The
UHCI driver and hardware handle the connection and initialization process from that
point on. The EHCI driver and hardware handle the perceived disconnect.
4. Configure Flag = 1 and a high-speed-capable Device is connected
— In this case, the EHC is the owner of the port before, and remains the owner after, the
connect occurs. The EHCI driver handles the connection and performs the port reset.
After the reset process completes, the EHC hardware has set the Port Enable bit in the
EHC’s PORTSC register. The port is functional at this point. The UHC continues to see an
unconnected port.
Device Disconnects
The Enhanced Host Controller Interface Specification for Universal Serial Bus, Revision 1.0
describes the details of handling Device Connects in Section 4.2. There are three general scenarios
that are summarized below.
1. Configure Flag = 0 and the device is disconnected
— In this case, the UHC is the owner of the port both before and after the disconnect occurs.
The EHC (except for the port-routing logic) never sees a device attached. The UHCI
driver handles disconnection process.
2. Configure Flag = 1 and a full-speed/low-speed-capable Device is disconnected
— In this case, the UHC is the owner of the port before the disconnect occurs. The
disconnect is reported by the UHC and serviced by the associated UHCI driver. The
port-routing logic in the EHC cluster forces the Port Owner bit to 0, indicating that the
EHC owns the unconnected port.
3. Configure Flag = 1 and a high-speed-capable Device is disconnected
— In this case, the EHC is the owner of the port before, and remains the owner after, the
disconnect occurs. The EHCI hardware and driver handle the disconnection process. The
UHC never sees a device attached.
Intel^® I/O Controller Hub 6 (ICH6) Family Datasheet
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