Intel® IXP42X product line and IXC1100 control plane processors—PCI Controller
Intel® IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
DM September 2006
246 Order Number: 252480-006US
As described previously, during DMA transfers the DS bit in the DMA length registers controls byte-lane routing. Figure 51 shows the byte lane routing between the PCI bus and the South AHB during DMA transfers. The DMA channels are word-only accesses.Figure 50. Byte Lane Routing During AHB Memory Mapped Accesses of the PCI Bus – AHB configured as a Little-Endian Bus
31 24
Write,
pci_csr.ADS = 1
AHB Data
3210
23 16 15 870
31 24
11 10 01 00
23 16 15 870
31 24
3 2 10
23 16 15 870
31 24
11 10 01 00
23 16 15 870
AHB Data
PCI Data PCI Data
Read,
pci_csr.ADS = 1
31 24
Write,
pci_csr.ADS = 0
AHB Data
3210
23 16 15 870
31 24
11 10 01 00
23 16 15 870
31 24
3 2 10
23 16 15 870
31 24
11 10 01 00
23 16 15 870
AHB Data
PCI Data PCI Data
Read,
pci_csr.ADS = 0