IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 212 / 744

IDT SMBus Interfaces
PES32NT24xG2 User Manual 12 - 8 January 30, 2013
Notes
Figure 12.7 Wait Configuration Block
When configuring the PES32NT24xG2 device via EEPROM, the Wait configuration block can be used to
ensure that actions performed by previously loaded configuration blocks have completed before proceeding
with EEPROM loading. This capability is particularly useful during partition and port configuration (see
Chapter 5), as it makes it possible to program the EEPROM instruction sequence to wait for a partition state
change or port mode change to complete (i.e., by waiting on the appropriate bits in the SWPARTxSTS and
SWPORTxSTS registers respectively) before proceeding with subsequent configurations.
Care must be taken when using the Wait configuration block to check for the completion of partition
state changes or port operating mode changes. In particular, note that writing to the STATE field in the
SWPARTxCTL register without modifying the value of this field does not constitute a partition state change;
therefore, it would be an error to use the Wait configuration block to check that the state change has
completed. Similarly, writing to the MODE, SWPART, or DEVNUM fields in the SWPORTxCTL register
without modifying their values does not constitute a port operating mode change.
Care must be taken when using the Wait configuration block, as excessive waiting periods will elongate
the time it takes to load the EEPROM. This can potentially cause the switch to remain in quasi-reset mode
for periods approximating the 1 second limit imposed by the PCI Express Base Specification for devices to
successfully complete a configuration request. Refer to section Partition Resets on page 3-11 for details.
The final type of configuration block is the configuration done sequence which is used to signify the end
of a serial EEPROM initialization sequence.
The configuration done sequence consists of two fields and its format is shown in Figure 12.8. The CFG
TYPE field is always 0x7 for configuration done sequences. The CHECKSUM field contains the checksum
of all of the bytes in all of the fields read from the serial EEPROM from the first configuration block to the
end of this done sequence, including configuration jump blocks.
Bit
0
Bit
1
Bit
2
Bit
3
Bit
4
Bit
5
Bit
6
Bit
7
Byte 1 SYSADDR[9:2]
CFG TYPE
0x3
Byte 0
Byte 3 DATA[7:0]
Byte 4 DATA[15:8]
Byte 5 DATA[23:16]
Byte 6 DATA[31:24]
Byte 2 SYSADDR[17:10]
Reserved
(must be zero)
Byte 7 MASK[7:0]
Byte 8 MASK[15:8]
Byte 9 MASK[23:16]
Byte 10 MASK[31:24]