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194 AMD Geode™ SC1200/SC1201 Processor Data Book
Core Logic Module - Bridge, GPIO, and LPC Registers - Function 0
32579B
1 Power Management Configuration Trap. If this bit is set to 1 and an access occurs to one of the configuration registers in
PCI Function 1 (F1) register space, an SMI is generated. Writes are trapped; access to the register is denied. Reads are
snooped; access to the register is allowed.
0: Disable.
1: Enable.
Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[9].
Second level SMI status is reported at F1BAR0+I/O Offset 04h/06h[5].
0 Legacy Configuration Trap. If this bit is set to 1 and an access occurs to one of the configuration registers in PCI Function
0 (F0), an SMI is generated. Reads and writes are snooped; access to the register is allowed.
0: Disable.
1: Enable.
Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[9].
Second level SMI status is reported at F1BAR0+I/O Offset 04h/06h[5].
Index 42h Reserved Reset Value: 00h
Index 43h Delayed Transactions Register (R/W) Reset Value: 02h
7:6 Reserved. Must be set to 0.
5 Reserved. Must be set to 1.
4 Enable PCI Delayed Transactions for Access to I/O Address 170h-177h (Secondary IDE Channel). PIO mode uses
repeated I/O transactions that are faster when non-delayed transactions are used.
0: I/O addresses complete as fast as possible on PCI. (Default)
1: Accesses to Secondary IDE channel I/O addresses are delayed transactions on PCI.
For best performance of VIP, this bit should be set to 1 unless PIO mode 3 or 4 are used.
3 Enable PCI Delayed Transactions for Access to I/O Address 1F0h-1F7h (Primary IDE Channel). PIO mode uses
repeated I/O transactions that are faster when non-delayed transactions are used.
0: I/O addresses complete as fast as possible on PCI. (Default)
1: Accesses to Primary IDE channel I/O addresses are delayed transactions on PCI.
For best performance of VIP, this bit should be set to 1 unless PIO mode 3 or 4 are used.
2 Enable PCI Delayed Transactions for AT Legacy PIC I/O Addresses. Some PIC status reads are long. Enabling delayed
transactions help reduce DMA latency for high bandwidth devices like VIP.
0: PIC I/O addresses complete as fast as possible on PCI. (Default)
1: Accesses to PIC I/O addresses are delayed transactions on PCI.
For best performance of VIP, this bit should be set to 1.
1 Enable PCI Delayed Transactions for AT Legacy PIT I/O Addresses. Some x86 programs (certain benchmarks/diagnos-
tics) assume a particular latency for PIT accesses; this bit allows that code to work.
0: PIT I/O addresses complete as fast as possible on PCI.
1: Accesses to PIT I/O addresses are delayed transactions on PCI. (Default)
For best performance (e.g., when running Microsoft
®
Windows
®
), this bit should be set to 0.
0 Reserved. Must be set to 0.
Index 44h Reset Control Register (R/W) Reset Value: 01h
7 AC97 Soft Reset. Active low reset for the AC97 codec interface.
0: AC97_RST# is driven high. (Default)
1: AC97_RST# is driven low.
6:4 Reserved. Must be set to 0.
3 IDE Controller Reset. Reset the IDE controller.
0: Disable.
1: Enable.
Write 0 to clear. This bit is level-sensitive and must be cleared after the reset is enabled.
Table 6-29. F0: PCI Header/Bridge Configuration Registers for GPIO and LPC Support (Continued)
Bit Description