Intel 82540EP/EM Network Card User Manual


 
88 Software Developer’s Manual
PCI Local Bus Interface
Figure 4-4. Master Write Command Usage Algorithm
4.3.1.1 MWI Bursts
If there is at least one cache line of data remaining, then the Ethernet controller continues the
MWI burst.
If there is not at least one cache line of data remaining, then the Ethernet controller terminates
the transaction on the boundary, re-acquires the bus, and issues a MW command for the
remainder of data.
If the transaction is terminated prematurely due to a target disconnect or latency time-out, the
Ethernet controller re-evaluates command usage based on the new start address and the
amount of remaining data.
!Aligned || (Aligned && (Count < CLS)) || !MWI_Enable
IDLE
Write Command
Determination
MW
Burst
MWI
Burst*
Terminate
Transaction
MWI
Boundary
Evaluation
Boundary || Terminate
Aligned && (Count >= CLS)
Cnt_Rmn = 0
Cnt_Rmn = 0
!MWI_Enable ||
(!Aligned || Cnt_Rmn < CLS)
MWI_Enable &&
d && Cnt_Rmn >= CLS)
Cnt_Rmn
= Remaining data for XFR
CLS
= Cache line size
Boundary
= At cache line boundary?
Aligned
= Address aligned to cache line boundary
Count
= Amount of data for XFR
Wr_Req || (Cnt_Rmn != 0)
Wr_Req
= Initial request for master write
* Either the initiation or continuation of the MWI Burst
Terminate
Terminate
= Target disconnect or latency timer ex