2.13 EDMA3 Prioritization
2.13.1 Channel Priority
Event
Register
(ER/ERH)
Event
Enable
Register
(EER/EERH)
Event
Trigger
Event
Set
Register
(ESR/ESRH)
Manual
Trigger
Chained
Event
Register
(CER/CERH)
Chain
Trigger
QDMA
Event
Register
(QER)
QDMA Trigger
64
64
64
64:1PriorityEncoder
8:1PriorityEncoder
8
Queue 0
Queue 1
Queue Bypass
15
0
15
0
Event
Queues
ChannelMapping
Parameter
Set 0
Parameter
Set 1
Parameter
Set 126
Parameter
Set 127
PaRAM
T
ransferRequestSubmission
Completion
Detection
Completion
Interface
Completion
Interrupt
Error
Detection
E0
E1
E63
TC0
TC1
SCR
EDMA3 Channel
Controller
From
EDMA3TC0
From
EDMA3TC1
EDMA3CC_ERRINT
EDMA3CC_INT[2:0]
to ARM/IMCOP
From Peripheral/External Events
Trigger Source Priority
Channel Priority
Dequeue Priority
System Priority
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EDMA3 Prioritization
The EDMA3 controller has many implementation rules to deal with concurrent events/channels, transfers,
etc. The following subsections detail various arbitration details whenever there might be occurrence of
concurrent activity.
shows the different places EDMA3 priorities come into play.
The DMA event registers (ER and ERH) capture up to 64 events; likewise, the QDMA event register
(QER) captures QDMA events for all QDMA channels; therefore, it is possible for events to occur
simultaneously on the DMA/QDMA event inputs. For events arriving simultaneously, the event associated
with the lowest channel number is prioritized for submission to the event queues (for DMA events,
channel 0 has the highest priority and channel 63 has the lowest priority; similarly, for QDMA events,
channel 0 has the highest priority and channel 7 has the lowest priority). This mechanism only sorts
simultaneous events for submission to the event queues.
If a DMA and QDMA event occurs simultaneously, the DMA event always has prioritization against the
QDMA event for submission to the event queues.
Figure 2-14. EDMA3 Prioritization
SPRUG34 – November 2008
EDMA3 Architecture
61
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