
56
Functional Operation
Chapter 3
AMD-8111 HyperTransport I/O Hub Data Sheet
24674
Rev. 3.00
April 2003
AMD Preliminary Information
Figure 8.
Device Monitors and Retrigger Timers
3.7.1.2.1
Traps
Configuration registers DevB:3x[D8:B4] specify several traps for memory, I/O, and configuration
space address ranges. These traps are generated for the specified transactions that (1) are targeted at
the IC or any device on or behind the secondary PCI bus or any devices on the LPC bus, (2) are not
targeted to the configuration space or I/O space of the IDE controller, and (3) are not targeted at any
of the DevA:0x[FF:C0] configuration registers.
3.7.1.3
System Inactivity Timer
Any of the hardware traps, IRQ lines, or PCI bus master activity can be enabled to reload the system
inactivity timer (SIT). If the SIT decrements to zero, then, if enabled, an interrupt is generated.
3.7.1.4
Throttling Logic
When throttling, the IC repetitively places the processor into the Stop Grant state for a specified
percentage of time in order to reduce the power being consumed by the processor. STPCLK_L is used
to control the processor Stop Grant state with a period specified by DevB:3x40[NTPER, TTPER] and
a duty cycle specified by DevB:3x40[THMINEN], DevB:3x4D and PM10.
Two types of throttling are possible: normal and thermal. Normal throttling is controlled by software.
Thermal throttling is controlled by the THERM_L pin (see also DevB:3x40[TH2SD]). If both are
triggered active simultaneously, then the duty cycle specified for thermal throttling is used. Throttling
is only possible when in the FON state. If throttling is enabled when entering other states, then it
stops; after exiting the state, throttling resumes.
3.7.1.5
CLKRUN_L PCI Bus Clock Control
PCI bus clock control is performed with the CLKRUN_L signal and associated protocol as defined by
the PCI Mobile Design Guide. The IC is the “Central Resource” with regard to CLKRUN_L protocol.
3.7.1.5.1
Enabling PCI CLKRUN_L Protocol
CLKRUN_L protocol is enabled by PMC5. CLKRUN_L assertion by an external device is ignored
during the S1 sleep state.
Reload Retrigger
Timer
Re-trigger
Timer Time Out
OR
OR
STS bit in
PMA0
Interrupt
Select
DMA Request
Select
Address
Decode