MSC8144E Reference Manual, Rev. 3
17-6
Freescale
Semiconductor
RapidIO Interface Dedicated DMA Controller
3.
Set the mode register channel transfer mode bit, MRn[CTM], and the single-write start
direct mode bit, MRn[SRW]. Other control parameters may also be initialized in the
mode register. Set MRn[CDSM/SWSM] for transfers started using SARn. Clear
MRn[CDSM/SWSM] for transfers started using the DARn.
4.
A write to the source or destination address register starts the DMA transfer and
automatically sets MRn[CS].
5.
SRn[CB] is set by the DMA controller to indicate the DMA transfer is in progress.
6.
SRn[CB] is automatically cleared by the DMA controller after the transfer is finished, or
if the transfer is aborted (MRn[CA] transitions from a 0 to 1), or if a transfer error
occurs.
7.
End of segment interrupt is generated if MRn[EOSIE] is set.
17.2.1.1.3 Basic Chaining Mode
In basic chaining mode, software must first build link descriptor segments in memory. Then the
current link descriptor address register must be initialized to point to the first descriptor in
memory. The DMA controller loads descriptors from memory prior to a DMA transfer. The
DMA controller begins the transfer according to the link descriptor information loaded for the
segment. After the current segment is finished, the DMA controller reads the next link descriptor
from memory and begins another DMA transfer. The transfer is finished if the current link
descriptor is the last one in memory or if an error condition occurs. The sequence of events to
start and complete a transfer in chaining mode is as follows:
1.
Build link descriptor segments in memory.
2.
Poll the channel state (see Table 17-2), to confirm that the specific DMA channel is
idle.
3.
Initialize CLNDARn to point to the first link descriptor in memory.
4.
Clear the mode register channel transfer mode bit, MRn[CTM], as well as MRn[XFE],
to indicate basic chaining mode. Other control parameters may also be initialized in the
mode register.
5.
Clear, then set the mode register channel start bit, MRn[CS], to start the DMA transfer.
6.
SRn[CB] is set by the DMA controller to indicate the DMA transfer is in progress.
7.
SRn[CB] is automatically cleared by the DMA controller after finishing the transfer of
the last descriptor segment, or if the transfer is aborted (MRn[CA] transitions from a 0
to 1), or if an error occurs during any of the transfers.
17.2.1.1.4 Basic Chaining Single-Write Start Mode
Basic chaining single-write start mode allows a chain to be started by writing the current link
descriptor address register (CLNDARn). Setting MRn[CDSM/SWSM] in the mode register
causes MRn[CS] to be automatically set when the current link descriptor address register is
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...