DMA disable callback (changes)
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DMAManager
» DMA callback routines
» DMA disable callback
DMA disable callback
| Entry | |
|---|---|
| R11 | Value of R2 from DMA_QueueTransfer call |
| R12 | Value of R5 from DMA_RegisterChannel call |
| Exit | |
|---|---|
| - | All registers preserved |
| Processor in IRQ or SVC mode |
| IRQ & FIQ status undefined |
Use
DMAManager assumes that the target device will start off with its DMA request line disabled. This call is made just after stopping a transfer in the DMA controller, in order to instruct the device driver to disable the DMA request line within the device, or to otherwise cleanup after the receipt/transmission of data.
Notes
If DMAManager needs to pause a transfer (e.g. due to memory being moved), this callback will be called to disable the DMA request. Once it is safe to resume the transfer the DMA enable callback will be called again to re-enable it.
This documentation only covers the RISC OS 5 version of the DMAManager SWIs. For other OS versions, consult the appropriate PRM volume (e.g. volume 5a).
See also
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