
IDT Hot-Plug and Hot-Swap
PES34H16 User Manual
8 - 4
October 30, 2008
Notes
The state of a port’s Power Fault (PxPFN) input is not latched by the PES34H16. For proper operation
the system designer should ensure that once the PxPFN signal is asserted, it remains asserted until the
power enable (PxPEP) signal is toggled. This is required adapter behavior for the PCI Express Express-
Module form factor. Downstream port reset outputs are described in section Downstream Port Reset
Outputs on page 3-8.
The default value of hot-plug registers following a hot or fundamental reset may be configured via serial
EEPROM initialization. Since hot-plug I/O expander initialization occurs after serial EEPROM initialization,
the Command Completed (CC) bit is not set in the PCI Express Slot Status (PCIESSTS) register as a result
of serial EEPROM initialization.
Hot-Plug I/O Expander
the PES34H16 utilizes external SMBus/I2C-bus I/O expanders connected to the master SMBus inter-
face for hot-plug related signals associated with downstream ports. See section I/O Expanders on page 6-6
for details on the operation of the I/O expanders and for the mapping of downstream hot-plug signals to I/O
expander inputs and outputs.
Hot-Plug Interrupts and Wake-up
The hot-plug controller associated with a downstream slot may generate an interrupt or wake-up event.
Hot-plug interrupts are only generated when the Hot-Plug Interrupt Enable (HPIE) bit is set in the corre-
sponding port’s PCI Express Slot Control (PCIESCTL) register. The following bits, when set in the PCI
Express Slot Status (PCIESSTS) register, generate an interrupt if not masked by the corresponding bit in
the PCI Express Slot Control (PCIESCTL) register or by the HPIE bit: the Attention Button Pressed (ABP),
Power Fault Detected (PFD), MRL Sensor Changed (MRLSC), Presence Detected Changed (PDC), and
Command Completed (CC).
When an unmasked hot-plug interrupt is generated, the action taken is determined by the MSI Enable
(EN) bit in the MSI Capability (MSICAP) register and the Interrupt Disable (INTXD) bit in the PCI Command
(PCICMD) register. When the downstream port or the entire switch is in a D3
hot
state, then the hot-plug
controller generates a wake-up event using a PM_PME message instead of an interrupt if the event inter-
rupt is not masked in the slot control (PCIESCTL) register and hot-plug interrupts are disabled by the HPIE
bit. If the event interrupt is not masked and hot-plug interrupts are enabled, then both a PM_PME and an
interrupt are generated. If the event interrupt is masked, then neither a PM_PME or interrupt are generated.
Note that a command completed (CC bit) interrupt will not generate a wake-up event.
Legacy System Hot-Plug Support
Some systems require support for operating systems that lack PCIe hot-plug support. The PES34H16
supports these systems by providing a General Purpose Event (GPEN) output as an alternate function of
GPIO[5] that can be used instead of the INTx, MSI, and PME mechanisms defined by PCI Express hot-
plug.
Associated with each downstream port’s hot-plug controller is a bit in the General Purpose Event
Control (P0_GPECTL) register. When this bit is set, then the corresponding PCIe base 1.1 hot-plug event
notification mechanisms are disabled for that port and INTx, MSI and PME events will not be generated by
that port due to hot-plug events. Instead, hot-plug events are signaled through assertion of the GPEN
signal.
GPEN is an alternate function of GPIO[5] and GPIO[5] will not be asserted when GPEN is asserted
unless it is configured to operate as an alternate function. Whenever a port signals a hot-plug event through
assertion of the GPEN signal, the corresponding port’s status bit in the General Purpose Event Status
(P0_GPESTS) register is set. A bit in the P0_GPESTS register can only be set if the corresponding port’s
hot-plug controller is configured to signal hot-plug events using the general purpose event (GPEN) signal
assertion mechanism.
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Страница 10: ...IDT Table of Contents PES34H16 User Manual iv October 30 2008 Notes...
Страница 12: ...IDT List of Tables PES34H16 User Manual vi October 30 2008 Notes...
Страница 18: ...IDT Register List PES34H16 User Manual xii October 30 2008 Notes...
Страница 40: ...IDT Upstream Port Failover PES34H16 User Manual 2 6 October 30 2008 Notes...
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...