
Public Version
www.ti.com
SDMA Functional Description
BUFFERING_DISABLE = 0) or hardware-destination-synchronized transfer.
11.4.19.4.8 Linked-List Channel Linking
Channel linking for inter and intra super block is supported for type 1, 2, and 3 descriptors.
Assume that CHx and CHz are linked-list channels using generic descriptors. If CHx is composed of N
descriptors and CHz is composed of M descriptors, then in nonfast mode,
CHx: CHx[Data1]-> CHx[DES1] -> .… -> CHx[DESN]->CHx[DataN + 1]
CHz: CHz[Data1]-> CHz[DES1] -> .… -> CHz[DESM]->CHz[DataM + 1]
It is possible to link CHx to CHz or CHx to itself after the completion of the CHx transfer (end of super
block). To do this, the user must set the
[15] ENABLE_LNK bit to 1 and the
[4:0] NEXTLCH_ID bit to z (or to x for self linking) through the last descriptor using a
type 1 descriptor. The sequence is:
CHx: CHx[Data1]-> CHx[DES1] -> .… -> CHx[DESN]->CHx[DataN+1] -> CHz: CHz[Data1]-> CHz[DES1]
-> .… -> CHz[DESM]->CHz[DataM+1]
It is also possible to link CHx to CHz during the CHx transfer and before the end of super block. The user
must set the
[15] ENABLE_LNK bit to 1 and the
[4:0]
NEXTLCH_ID bit to z through descriptor p (CHx[DESp]) using a type 1 descriptor. The sequence is:
CHx: CHx[Data1]-> CHx[DES1] ->.…-> CHx[DESp]->CHx[Data(p + 1)] -> CHz[Data1]-> CHz[DES1] -> .…
The user must continue the linking until channels CHx and CHz complete their super-block transfers;
otherwise, the channels remain enabled.
NOTE:
In channel linking, the head of a chain can be in fast mode or nonfast mode. All channels
that are not in the head of the chain can be in nonfast mode only. In self-linking, the channel
cannot be in fast mode.
NOTE:
If channel CHx links to CHz in the middle of the superblock transfer (remember link bit can
be set through Type-1 descriptor load), CHx will get disabled after the corresponding data
load and enables the channel CHz.
2367
SWPU177N – December 2009 – Revised November 2010
SDMA
Copyright © 2009–2010, Texas Instruments Incorporated