
IDT Power Management
PES34H16 User Manual
7 - 3
October 30, 2008
Notes
When the PES34H16 receives a PME_Turn_Off message it broadcasts the PME_Turn_Off message on
all active downstream ports. The PES34H16 transmits a PME_TO_Ack message on its upstream port and
transitions its link state to L2/L3 Ready after it has received a PME_TO_Ack message on each of its down-
stream ports.
In order to avoid deadlock, a downstream port that does not receive a PME_TO_Ack message in the
time-out period specified in the PME_TO_Ack Time-Out (PMETOATO) field in its corresponding
PME_TO_Ack Timer (PMETOATIMER) register, declares a time-out, transitions its link to L2/L3 Ready and
signals to the upstream port that a PME_TO_Ack message has been received. If instead of being transi-
tioned to the D3
cold
state, the PES34H16 is transitioned to the D0
uninitialized
state, then the PES34H16
resumes generation of PM_PME messages.
Power Budgeting Capability
The PES34H16 contains the mechanisms necessary to implement the PCI express power budgeting
enhanced capability. However, by default, these mechanisms are not enabled. To enable the power
budgeting capability, registers in this capability should be initialized and the Next Pointer (NXTPTR) field in
the PCI Express VC Enhanced Capability Header (PCIEVCECAP) register should be initialized to point to
the power budgeting capability.
The power budgeting capability consists of the four power budgeting capability registers defined in the
PCIe 1.1 base specification and eight general purpose read-write registers. See section Power Budgeting
Enhanced Capability on page 9-57 for a description of these registers. The Power Budgeting Capabilities
(PWRBCAP) register contains the PCI express enhanced capability header for the power budgeting capa-
bility. By default, this register has an initial read-only value of zero. To enable the power budgeting capa-
bility, this register should be initialized via the serial EEPROM.
The Power Budgeting Data Value [0..7] (PWRBDV[0..7) registers are used to hold the power budgeting
information for that port in a particular operating condition. The PWRBDV registers may be read and written
when the Power Budgeting Data Value Unlock (PWRBDVUL) bit is set in the System Control (SYSCTL)
register. When the PWRBDVUL bit is cleared, these register are read-only and writes to these registers are
ignored. To enable the power budgeting capability, the PWRBDV registers should be initialized with power
budgeting information via the serial EEPROM.
Содержание 89HPES34H16
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Страница 86: ...IDT Power Management PES34H16 User Manual 7 4 October 30 2008 Notes...
Страница 172: ...IDT Configuration Registers PES34H16 User Manual 9 80 October 30 2008 Notes...