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1.1.12.3 Asynchronous CSC Interrupt Generation
The ASYNC_CSC bit (diagnostic register, PCI offset 93h, bit 0) controls the
CSC interrupt signaling method. If this bit is set to 0, then CSC is generated
synchronously to PCLK (recommended). By default this bit is set to 1, which
is the asynchronous mode.
1.1.12.4 CardBus Reserved Terminal Signaling
The CardBus interface has reserved terminals. Usually the CardBus controller
drives these terminals low. If the CBRSVD bit (system control register, PCI
offset 80h, bit 22) is set to 0, then the CardBus reserved terminal signals are
in a high-impedance state when a CardBus card is inserted in the socket.
1.1.12.5 Memory Burst R/W Operation Control
Memory read bursting is controlled via the MRBURSTDN bit (system control
register, PCI offset 80h, bit 15) for downstream burst transactions (PCI-to-PC
Card) and the MRBURSTUP bit (system control register, PCI offset 80h,
bit 14) for upstream burst transactions (PC Card-to-PCI). Memory write
bursting is controlled via the POSTEN bit (bridge control register, PCI offset
3Eh, bit 10). This bit enables write posting if disabled. No write data can be
accepted (including burst writes) until any previous write data has been
forwarded to its destination. By default, write posting and upstream read bursts
are disabled.
1.1.12.6 Power Savings Mode
The PCI445X device has a proprietary power-saving mode. It can be disabled
by changing the PWRSAVINGS bit (system control register, PCI offset 80h,
bit 6) to 0. When this bit is enabled (default), PCI CLOCK is internally gated
for a nonfunctioning circuit. For example, the CardBus interface does not
function when a 16-bit card is inserted. This power-saving mode will not
degrade performance; therefore, the default setting is recommended.
1.1.12.7 PME/RI_OUT Terminal Control Clarification
PME/RI_OUT terminal can be set up to signal a combination of these events.
The terminal is set up using the PME/RI_OUT bit (system control register, PCI
offset 80h, bit 0), the RIENB bit (card control register, PCI offset 91h, bit 7), and
PME enable bit (power management control/status, PCI offset A4h, bit 8). If
the terminal is set up as RI_OUT
and RIENB has ring indicate enabled, then
this signal follows the RI_OUT signal for 16-bit I/O cards. If RIENB has ring
indicate disabled but PME has PME enabled, then this line reflects the state
of the PMESTAT bit (power management control/status, PCI offset A4h,
bit 15). If both PME
and ring indicate are disabled, then the line remains high.
If the line is configured as PME and PME is enabled, then this line follows the
state of the PMESTAT bit; otherwise, the line remains high.
1.1.12.8 CLKRUN Control
PCLK can be kept running using CLKRUN protocol by setting the KEEPCLK
bit (system control register, PCI offset 80h, bit 1) to 1.