
IDT Clocking, Reset and Initialization
PES16T4G2 User Manual
2 - 7
January 28, 2013
Notes
When a Downstream Secondary Bus Reset occurs, the following sequence is executed.
1. If the corresponding downstream port’s link is up, TS1 ordered sets with the hot reset bit set are
transmitted
2. All TLPs received from corresponding downstream port and queued in the PES16T4G2 are
discarded.
3. Wait for software to clear the Secondary Bus Reset (SRESET) bit in the upstream port’s Bridge
Control Register (BCTL).
4. Normal downstream port operation begins.
The operation of the upstream port is unaffected by a Downstream Secondary Bus Reset.
The operation of other downstream ports is unaffected by a Downstream Secondary Bus Reset.
During a Downstream Secondary Bus Reset, Type 0 configuration read and write transactions that
target the downstream port complete normally.
During a Downstream Secondary Bus Reset, all TLPs destined to the secondary side of the downstream
port’s PCI-to-PCI bridge are treated as unsupported requests.
The operation of the slave SMBus interface is unaffected by a Downstream Secondary Bus Reset.
Downstream Port Reset Outputs
Individual downstream port reset outputs (P2RSTN, P4RSTN and P6RSTN) are provided as GPIO pin
alternate functions.
Following a Fundamental Reset, all of the GPIO pins default to GPIO inputs. Therefore, the downstream
port resets are tri-stated. A system designer should use a pull-down on these signals if they are used as
reset outputs.
The PES16T4G2 ensures through hardware that the minimum PxRSTN assertion pulse width is no less
than 200 µ s.
Downstream port reset outputs can be configured to operate in one of two modes. These modes are
power enable controlled reset output and power good controlled reset output. The downstream port reset
output mode is determined by the Reset Mode (RSTMODE) field in the Hot-Plug Configuration Control
(HPCFGCTL) register.
Power Enable Controlled Reset Output
In this mode a downstream port reset output state is controlled as a side effect of slot power being
turned on or off. The operation of this mode is illustrated in Figure 2.3.
A downstream port’s slot power is controlled by the Power Controller Control (PCC) bit in the PCI
Express Slot Control (PCIESCTL) register
Figure 2.3 Power Enable Controlled Reset Output Mode Operation
While slot power is disabled, the corresponding downstream port reset output is asserted.
PxPEP
PxRSTN
T
PWR2RST
T
RST2PWR
Содержание 89HPES16T4G2
Страница 10: ...IDT Table of Contents PES16T4G2 User Manual iv January 28 2013 Notes...
Страница 12: ...IDT List of Tables PES16T4G2 User Manual vi January 28 2013 Notes...
Страница 14: ...IDT List of Figures PES16T4G2 User Manual viii January 28 2013 Notes...
Страница 18: ...IDT Register List PES16T4G2 User Manual xii January 28 2013 Notes...
Страница 30: ...IDT PES16T4G2 Device Overview PES16T4G2 User Manual 1 12 January 28 2013 Notes...
Страница 48: ...IDT Link Operation PES16T4G2 User Manual 3 10 January 28 2013 Notes...
Страница 68: ...IDT SMBus Interfaces PES16T4G2 User Manual 5 18 January 28 2013 Notes...
Страница 72: ...IDT Power Management PES16T4G2 User Manual 6 4 January 28 2013 Notes...
Страница 140: ...IDT Configuration Registers PES16T4G2 User Manual 8 62 January 28 2013 Notes...