2-12
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Hawk PCI Host Bridge & Multi-Processor Interrupt Controller
2
threshold should be lowered to anticipate any additional latencies incurred
by the PPC Master on the PPC60x bus.
summarizes the PHB
available write posting options.
The PPC Master has an optional read ahead mode controlled by the RAEN
bit in the PSATTx registers that allows the PPC Master to prefetch data in
bursts and store it in the PCI FIFO. The contents of the PCI FIFO is then
used to satisfy the data requirements for the remainder of the PCI read
transaction. The PHB read ahead mechanism is tuned for maximum
efficiency during typical operation conditions. If excessive latencies are
encountered on the PPC60x bus, it may be necessary to tune the read ahead
mechanism to compensate for this. Additional tuning of the read-ahead
function is controlled by the RXFT/RMFT (Read Any FIFO
Threshold/Read Multiple FIFO Threshold) fields in the PSATTx registers.
These fields can be used to characterize when the PPC Master continues
reading ahead with respect to the PCI FIFO threshold. The FIFO threshold
should be raised to anticipate any additional latencies incurred by the PPC
Master on the PPC60x bus.
summarizes the PHB available read
ahead options.
Table 2-3. PPC Master Write Posting Options
WXFT
WPEN
PPC60x Start
PPC60x Continuation
xx
0
FIFO = 1 dword
FIFO = 1 dword
00
1
FIFO >= 4 cache lines
FIFO >= 1 cache line
01
1
FIFO >= 3 cache lines
FIFO >= 1 cache line
10
1
FIFO >= 2 cache lines
FIFO >= 1 cache line
11
1
FIFO >= 1 cache lines
FIFO >= 1 cache line
Table 2-4. PPC Master Read Ahead Options
RXFT
RMFT
RAEN
PCI
Command
Initial
Read Size
Continuation
Subsequent
Read Size
xx
xx
0
Read
1 cache
line
PCI received
data and
FRAME_
asserted
1 cache line
Read Line
Summary of Contents for MVME5100 Series
Page 1: ...MVME5100 Single Board Computer Programmer s Reference Guide V5100A PG2 September 2001 Edition ...
Page 16: ...xvi ...
Page 20: ...xx ...
Page 28: ...xxviii ...
Page 62: ...1 34 Computer Group Literature Center Web Site Product Data and Memory Maps 1 ...
Page 278: ...3 88 Computer Group Literature Center Web Site System Memory Controller SMC 3 ...
Page 288: ...4 10 Computer Group Literature Center Web Site Hawk Programming Details 4 ...
Page 320: ...Index IN 12 Computer Group Literature Center Web Site I N D E X ...