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PXA300 Processor and PXA310 Processor
Vol. I: System and Timer Configuration Developers Manual
Doc. No. MV-TBD-00 Rev. A
CONFIDENTIAL
Copyright © 12/13/06 Marvell
Page 296
Document Classification: Proprietary Information
December 13, 2006
Not approved by Document Control. For review only.
11.3.1.2
Channel States
The following states apply to the DMA channels:
•
Uninitialized — occurs after a reset. DCSRx[STOPINTR] is set when uninitialized.
•
Not running — occurs when either a valid descriptor has been loaded into the DDADRx register during a
descriptor-fetch transfer or valid DSADRx, DTADRx, and DCMDx registers have been programmed during
a no-descriptor-fetch transfer, but the corresponding run bit, DCSRx[RUN], is not set. For a
no-descriptor-fetch transfer, DCSRx[STOPINTR] is not cleared when the DSADRx, DTADRx and DCMDx
registers are programmed. For a descriptor-fetch transfer, DCSRx[STOPINTR] is cleared when the DMA
controller updates the DDADRx register.
•
Running — For a descriptor-fetch transfer, after programming DDADRx and setting DCSRx[RUN], four
words of descriptors are fetched from the memory and DCSRx[STOPINTR] continues to be clear. For a
no-descriptor-fetch transfer, after programming the DSADRx, DTADRx and DCMDx registers and setting
DCSRx[RUN], the corresponding channel clears the DCSRx[STOPINTR], skips the “descriptor-fetch,
running” state and enters the “Wait for Request” or “Transfer Data” state (see
).
•
Wait for request — occurs as the channel waits for a request before it starts to transfer data;
DCSRx[STOPINTR] is clear.
•
Transfer data — transferring data between the source and the target; DCSRx[STOPINTR] is clear.
•
Channel error — the channel with the error remains in the stopped state until software clears the error
condition, re-initializes the channel, and sets the DCSRx[RUN] bit and the DCSRx[BUSERRINTR] bit. See
for details.
•
Stopped — the channel is stopped. DCSRx[STOPINTR] is set. For a no-descriptor-fetch transfer, a stopped
channel is re-initialized by updating the DSADRx, DTADRx and DCMDx registers, then setting
DCSRx[RUN]. For a descriptor-fetch transfer, a stopped channel is re-initialized by updating the DDADRx
register and setting DCSRx[RUN].
summarizes the DMAC channel states.