Time-Sharing On A Dma Port; Generic Channels - Texas Instruments OMAP5910 Technical Reference Manual

5.3 Generic Channels

5.3.1 Transfers
5.3.1.1 Transfer Sources and Destination
Figure 5–4. Time-Sharing on a DMA Port
This section discusses the following generic channel topics:
-
Transfers
-
Addressing modes
-
Data packing and bursting
-
Data alignment
-
Constraint on channel configuration parameters
-
Endianism
-
Interrupt generation
-
Memory space protection
Each DMA channel can be configured independently from other channels.
This implies that a port can be shared by several channel requests. Therefore,
these requests are time-multiplexed by the port.
For example, in Figure 5–4 a DMA port must service requests from three DMA
channels:
-
Channel 0 as a source port (read requests, r
-
Channel 3 as a destination port (write requests, w
-
Channel 5 as a destination port (write requests. w
Figure 5–4 shows how these requests are multiplexed in time by the port.
r , r
0
Requests
waiting for w , w
3
service
w , w
5
A system DMA port can handle 10 read requests and 10 write requests (all the
possible requests in the DMA) simultaneously.
, r
0 0
, w Port
3 3
, w
5 5
Generic Channels
)
0
)
3
)
5
Requests served
w , w , r , w , w , r
5 3 0 5 3
System DMA Controller
, w , w , r
0 5 3 0
5-9