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5-14 C141-E203-01EN
The host uses the DMA Active - Device to Host FIS layout. This FIS instructs the
host to continue transferring DMA data from the host to the device.
5.2.3.5 DMA Setup - Device to Host or Host to Device (Bidirectional)
The DMA Setup - Device to Host or Host to Device FIS has the following layout:
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0
9
8
7
6 5 4 3 2 1
0
Reserved (0) Reserved (0) A
I
D
Reserved (0)
FIS Type (41h)
0
0 TAG
1
0
2
Reserved (0)
3
DMA Buffer Offset
4
DMA Transfer Count
5
Reserved (0)
6
Figure 5.6 DMA Setup - Device to Host or Host to Device FIS layout
The DMA Setup - Device to Host or Host to Device FIS communicates the start of
a first-party DMA access to the host system. This FIS is used to request the host
system or device to set up the DMA controller before the start of a DMA data
transfer.
A - Auto Active bit. If this bit is cleared ("0" is set for the bit), it indicates that a
DMA Active FIS transfer is required before a Data FIS transfer.
D - Direction bit. If this bit is set ("1" is set for the bit), it indicates that the data
transfer direction is from the device to the host system.