Datasheet

Functional Description
Intel® Xeon® Processor D-1500 Product Family 141
Datasheet - Volume 1 of 4: Integrated Platform Controller Hub
March 2015
— The DATA_LEN_CNT field is updated to show the number of bytes that were
received after the PID.
4. If a valid packet was received from the device that was one byte in length
(indicating it was a handshake packet), then the debug port controller:
— Resets the ERROR_GOOD#_STS bit
— Sets the DONE_STS bit
5. If a valid packet was received from the device that was more than one byte in
length (indicating it was a data packet), then the debug port controller:
— Transmits an ACK handshake packet
— Resets the ERROR_GOOD#_STS bit
— Sets the DONE_STS bit
6. If no valid packet is received, then the debug port controller:
— Sets the EXCEPTION_STS field to 001b
— Sets the ERROR_GOOD#_STS bit
— Sets the DONE_STS bit.
3.17.9.1.3 Debug Software
Enabling the Debug Port
There are two mutually exclusive conditions that debug software must address as part
of its startup processing:
• The EHCI has been initialized by system software
• The EHCI has not been initialized by system software
Debug software can determine the current ‘initialized’ state of the EHCI by examining
the Configure Flag in the EHCI USB 2.0 Command Register. If this flag is set, then
system software has initialized the EHCI. Otherwise, the EHCI should not be considered
initialized. Debug software will initialize the debug port registers depending on the
state of the EHCI. However, before this can be accomplished, debug software must
determine which root USB port is designated as the debug port.
Determining the Debug Port
Debug software can easily determine which USB root port has been designated as the
debug port by examining bits 20:23 of the EHCI Host Controller Structural Parameters
register. This 4-bit field represents the numeric value assigned to the debug port (that
is, 0001=port 1).
Debug Software Startup with Non-Initialized EHCI
Debug software can attempt to use the debug port if after setting the OWNER_CNT bit,
the Current Connect Status bit in the appropriate (See Determining the Debug Port
Presence) PORTSC register is set. If the Current Connect Status bit is not set, then
debug software may choose to terminate or it may choose to wait until a device is
connected.
If a device is connected to the port, then debug software must reset/enable the port.
Debug software does this by setting and then clearing the Port Reset bit the PORTSC
register. To ensure a successful reset, debug software should wait at least 50 ms before