IDT Clocking, Reset and Initialization
PES12T3G2 User Manual
2 - 5
January 28, 2013
Notes
Figure 2.2 Fundamental Reset Using RSTHALT to Keep Device in Quasi-Reset State
Hot Reset
A hot reset may be initiated by any of the following conditions:
–
Reception of TS1 ordered-sets on the upstream port indicating a hot reset.
–
Data link layer of the upstream port transitions to the DL_Down state.
–
Writing a one to the Hot Reset (HRST) bit in the Switch Control (SWCTL) register.
The initiation of a hot reset due to the data link layer of the upstream port transitioning to the DL_Down
state may be disabled by setting the Disable Link Down Hot Reset (DLDHRST) bit in the Switch Control
(SWCTL) register. Other hot reset conditions are unaffected by this bit.
When a hot reset occurs, the following sequence is executed.
1. Each downstream port whose link is up propagates the hot reset by transmitting TS1 ordered sets
with the hot reset bit set.
2. All of the logic associated with the PES12T3G2 except the PLLs, SerDes, master SMBus interface,
and slave SMBus interface is reset.
3. All registers fields in all registers, except those denoted as “sticky” or Read and Write when Unlocked
(i.e, RWL), are reset to their initial value. The value of fields denoted as “sticky” or RWL is preserved
across a hot reset.
4. Link training begins. While link training is in progress, proceed to step 5.
5. The PCI Express stacks and associated logic are held in a quasi-reset state in which the following
actions occur.
–
All links enter an active link training state within 20 ms of the clearing of the hot reset condition.
–
Within 100 ms of the clearing of the Hot Reset condition, all of the stacks are able to process
configuration transactions and respond to these transactions with a configuration request retry
status completion. All other transactions are ignored.
6. If the selected switch operating mode is one that requires initialization from the serial EEPROM and
the Disable Hot Reset Serial EEPROM Initialization (DHRSTSEI) bit is not set in the Switch Control
(SWCTL) register, then the contents of the serial EEPROM are read and the appropriate
PES12T3G2 registers are updated.
SerDes
Slave SMBus
CDR Reset & Lock
Ready for Normal Operation
Ready for Normal Operation
Notes:
1ms max
20 ms max.
Stacks held in Quasi-Reset Mode
Link Training
PLL Lock
RSTHALT
RSTHALT bit in SWCTL register is set
RSTHALT bit in SWCTL cleared (i.e., by slave SMBus)
PExREFCLKP/N
Vdd
PERSTN
Tpvperl
Tperst-clk
1) Reference Clock (REFCLK) not shown to scale.
2) The PES12T3G2 requires a minimum time for Tperst-clk of 1µs. The PES12T3G2 requires a minimum time for Tpvperl of 1ms.
3) In a system, the values of Tpvperl and Tperst-clk depend on the mechanical form factor in which the PES12T3G2 is used. For example,
the PCIe Card Electromechanical Specification, Revision 2.0, specifies minimum values of Tperst-clk=100µs and Tpvperl=100ms.
Содержание 89HPES12T3G2
Страница 10: ...IDT Table of Contents PES12T3G2 User Manual iv January 28 2013 Notes...
Страница 12: ...IDT List of Tables PES12T3G2 User Manual vi January 28 2013 Notes...
Страница 14: ...IDT List of Figures PES12T3G2 User Manual viii January 28 2013 Notes...
Страница 18: ...IDT Register List PES12T3G2 User Manual xii January 28 2013 Notes...
Страница 46: ...IDT Link Operation PES12T3G2 User Manual 3 10 January 28 2013 Notes...
Страница 66: ...IDT SMBus Interfaces PES12T3G2 User Manual 5 18 January 28 2013 Notes...
Страница 70: ...IDT Power Management PES12T3G2 User Manual 6 4 January 28 2013 Notes...
Страница 138: ...IDT Configuration Registers PES12T3G2 User Manual 8 62 January 28 2013 Notes...