2.7.2 Channel Controller Regions
2.8
Chaining EDMA3 Channels
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Chaining EDMA3 Channels
An EDMA3 transfer is programmed/configured by the ARM. In order to provide autonomous operation for
each master, the EDMA3 channel controller allows partitioning of the resources between different masters
via the shadow regions. There are four EDMA3 shadow regions (and its associated memory maps). The
first shadow region is associated to the EDMA3 programmers (ARM) that have read/write access to the
memory-mapped registers of the EDMA3CC. The remaining three shadow regions are reserved and
should not be used.
Associated with each shadow region are a set of registers defining which channels and interrupt
completion codes belong to that region. These registers are user-programmed per region, in order to
assign ownership of the DMA/QDMA channels to a region.
•
DRAE
m
and DRAEH
m
: One register pair exists for the ARM shadow region. The number of bits in
each register pair matches the number of DMA channels (64 DMA channels). These registers need to
be programmed to assign ownership of DMA channels and interrupt (or TCC codes) to the respective
region. Accesses to DMA and interrupt registers via the shadow region address view are filtered
through the DRAE/DRAEH pair. A value of 1 in the corresponding DRAE(H) bit implies that the
corresponding DMA/interrupt channel is accessible; a value of 0 in the corresponding DRAE(H) bit
forces writes to be discarded and returns a value of 0 for reads.
•
QRAE: The number of bits in the register matches the number of QDMA channels (8 QDMA
channels).These registers need to be programmed to assign ownership of QDMA channels to the
respective region. To enable a channel in a shadow region, using shadow region 0 QEER, writing into
QEESR will not have the desired effect if the respective bit in QRAE is not set.
The EDMA3CC has four DMA region access registers (DRAE0-3 and DRAEH0-3) and four QDMA region
access registers (QRAE0-3).
provides the shadow region and region access registers assignment to each of the EDMA3
masters.
Table 2-9. EDMA3 Shadow Regions
EDMA3 Master
Region
Region Access Registers
ARM
Shadow Region 0
DRAE0, DRAEH0, and QRAE0
-
Shadow Region 1
DRAE1, DRAEH1, and QRAE1
-
Shadow Region 2
DRAE2, DRAEH2, and QRAE2
-
Shadow Region 3
DRAE3, DRAEH3, and QRAE3
A value of 1 in a given bit position in the DMA/QDMA region access enable register corresponding to a
particular shadow region implies that the corresponding channel (and the corresponding bit position) can
be manipulated via the EDMA3 master associated to that shadow region. For example, DRAEH0 =
0000 0001h implies that DMA channel 32 (which is accessed at bit position 32) is manipulated by ARM
(shadow region 0).
Note:
An EDMA programmer is limited to only using the appropriate region via software
convention.
illustrates a judicious resource pool division across two regions, assuming the ARM needs to be allocated
16 DMA channels (0-15) and 4 QDMA channels (0, 3, 5, and 7) and 32 TCC codes (0-15 and 48-63). The
image coprocessor needs to be allocated 16 DMA channels (16-32) and the remaining 4 QDMA channels
(1, 2, 4, and 6) and TCC codes (16-47). DRAE should be equal to the OR of the bits required for the DMA
channels and the TCC codes:
The channel chaining capability for the EDMA3 allows the completion of an EDMA3 channel transfer to
trigger another EDMA3 channel transfer. The purpose is to allow you the ability to chain several events
through one event occurrence.
SPRUG34 – November 2008
EDMA3 Architecture
47
Содержание TMS320DM357
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