Data Integrity and Error Handling
6-30
Intel® 460GX Chipset Software Developer’s Manual
6.12.8
Error Conditions
6.12.8.1
WXB as Bus Master
6.12.8.1.1 Master Abort
If the WXB initiates a PCI transaction and no target responds, the WXB will terminate the
transaction with a master-abort. The WXB will wait five PCI clocks after asserting
FRAME#
for a
target to respond with
DEVSEL#
. If no target responds, the WXB will perform a master abort to
terminate the cycle on the PCI bus. Special Cycle commands, which are broadcast to all PCI
targets, will always be terminated with master abort and, therefore, are never considered an error.
Master aborts during other transactions (configuration, memory map, or I/O cycles) also are
generally not considered as errors. For writes, a normal completion packet will be returned to the
Chipset core. Reads will additionally return all 1’s as data.
When the WXB performs a master abort, it will log the event by setting the
PCISTS
register’s
Received Master Abort (
RMA
) bit, unless the transaction was a Special Cycle.
6.12.8.1.2 Received Target Disconnect
A PCI target may issue a disconnect to indicate it is unable to respond within the PCI latency
guidelines. Disconnect is signaled when the target asserts both
STOP#
and
DEVSEL#
. The target
controls whether another data transfer may occur by whether
TRDY#
is asserted when
STOP#
is
asserted. A target disconnect is not usually issued on the first data phase of the transaction. Target
disconnects are not considered errors, and are not logged or reported in any way. After a target
disconnect, the WXB will deassert its request signal and wait at least two PCI clocks before re-
arbitrating for the PCI bus to complete the transfer.
6.12.8.1.3 Received Target Retry
A PCI target may issue a retry to indicate that it is currently unable to process the transaction. Retry
is signaled when the target asserts
STOP#
and
DEVSEL#
and does not assert
TRDY#
. Retry is
actually a special case of disconnect that occurs before the first data transfer.
After receiving a retry for a transaction, the WXB will deassert its request line and wait at least two
PCI clocks before re-arbitrating for the PCI bus to retry the transaction. If the transaction is a write,
the WXB will retry the transaction until it succeeds. If the transaction is a read, the WXB will
reattempt the transaction until it succeeds, but may allow other reads and writes to pass it. Note, in
all of these cases the retries are not considered errors. There is no logging or error reporting of any
kind.
6.12.8.1.4 Received Target Abort
A PCI target may issue an abort to indicate that the current transaction should be terminated and
should not be attempted again. This is a catastrophic failure. Target abort is signaled when
STOP#
is asserted and
DEVSEL#
is deasserted. The WXB will log the target abort by setting the
PCISTS
register’s Received Target Abort (
RTA
) bit. The WXB then returns a hard fail response to the
Chipset core.
6.12.8.1.5 Data Parity Errors
When the WXB is the PCI bus master, it will check the data parity provided during read data
cycles, and watch for the assertion of
PERR#
during write data cycles. If a parity error is detected,
and the
PCICMD
registers
PERRE
bit is set, then the
PCISTS
register’s Detected Parity Error
Summary of Contents for 460GX
Page 1: ...Intel 460GX Chipset System Software Developer s Manual June 2001 Document Number 248704 001 ...
Page 20: ...Introduction 1 8 Intel 460GX Chipset Software Developer s Manual ...
Page 80: ...System Architecture 3 8 Intel 460GX Chipset Software Developer s Manual ...
Page 90: ...System Address Map 4 10 Intel 460GX Chipset Software Developer s Manual ...
Page 98: ...Memory Subsystem 5 8 Intel 460GX Chipset Software Developer s Manual ...
Page 146: ...AGP Subsystem 7 16 Intel 460GX Chipset Software Developer s Manual ...
Page 170: ...IFB Register Mapping 9 6 Intel 460GX Chipset Software Developer s Manual ...
Page 190: ...IFB Usage Considerations 10 20 Intel 460GX Chipset Software Developer s Manual ...
Page 232: ...LPC FWH Interface Configuration 11 42 Intel 460GX Chipset Software Developer s Manual ...
Page 244: ...IDE Configuration 12 12 Intel 460GX Chipset Software Developer s Manual ...
Page 258: ...Universal Serial Bus USB Configuration 13 14 Intel 460GX Chipset Software Developer s Manual ...
Page 270: ...SM Bus Controller Configuration 14 12 Intel 460GX Chipset Software Developer s Manual ...
Page 288: ...PCI LPC Bridge Description 15 18 Intel 460GX Chipset Software Developer s Manual ...
Page 294: ...IFB Power Management 16 6 Intel 460GX Chipset Software Developer s Manual ...