82801FB Datasheet, PDF (520/786 Pages) Intel Corporation – Intel I/O Controller Hub 6 (ICH6) Family

UHCI Controllers Registers
13.2.2
USBSTS—USB Status Register
I/O Offset:
Default Value:
Base + (02–03h)
0020h
Attribute:
Size:
R/WC
16 bits
This register indicates pending interrupts and various states of the host controller. The status
resulting from a transaction on the serial bus is not indicated in this register.
Bit
Description
15:6 Reserved
HCHalted — R/WC.
5 ^{0 = Software clears this bit by writing a 1 to it.}
1 = The host controller has stopped executing as a result of the Run/Stop bit being set to 0, either
by software or by the host controller hardware (debug mode or an internal error). Default.
Host Controller Process Error — R/WC.
0 = Software clears this bit by writing a 1 to it.
1 = The host controller has detected a fatal error. This indicates that the host controller suffered a
4
consistency check failure while processing a Transfer Descriptor. An example of a consistency
check failure would be finding an illegal PID field while processing the packet header portion of
the TD. When this error occurs, the host controller clears the Run/Stop bit in the Command
register (D29:F0/F1/F2/F3:BASE + 00h, bit 0) to prevent further schedule execution. A
hardware interrupt is generated to the system.
Host System Error — R/WC.
0 = Software clears this bit by writing a 1 to it.
1 = A serious error occurred during a host system access involving the host controller module. In a
3
PCI system, conditions that set this bit to 1 include PCI Parity error, PCI Master Abort, and PCI
Target Abort. When this error occurs, the host controller clears the Run/Stop bit in the
Command register to prevent further execution of the scheduled TDs. A hardware interrupt is
generated to the system.
Resume Detect (RSM_DET) — R/WC.
0 = Software clears this bit by writing a 1 to it.
2 _{1 = The host controller received a “RESUME” signal from a USB device. This is only valid if the}
Host controller is in a global suspend state (Command register, D29:F0/F1/F2/F3:BASE + 00h,
bit 3 = 1).
USB Error Interrupt — R/WC.
0 = Software clears this bit by writing a 1 to it.
1 _{1 = Completion of a USB transaction resulted in an error condition (e.g., error counter underflow). If}
the TD on which the error interrupt occurred also had its IOC bit (D29:F0/F1/F2/F3:BASE +
04h, bit 2) set, both this bit and Bit 0 are set.
USB Interrupt (USBINT) — R/WC.
0 = Software clears this bit by writing a 1 to it.
0 ^{1 = The host controller sets this bit when the cause of an interrupt is a completion of a USB}
transaction whose Transfer Descriptor had its IOC bit set. Also set when a short packet is
detected (actual length field in TD is less than maximum length field in TD), and short packet
detection is enabled in that TD.
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Intel^® I/O Controller Hub 6 (ICH6) Family Datasheet