Datasheet

06 February 2012 Broadcom Europe Ltd. 406 Science Park Milton Road Cambridge CB4 0WW Page 64
© 2012 Broadcom Corporation. All rights reserved
1. The internal data structure is 128 bits instead of 256 bits. This means that if you do
a 128 bit wide read burst of more than 1 beat, the DMA input register will be full
and the read bus will be stalled. The normal DMA engine can accept a read burst of
2 without stalling. If you do a narrow 32 bit read burst from the peripherals then
the lite engine can cope with a burst of 4 as opposed to a burst of 8 for the normal
engine. Note that stalling the read bus will potentially reduce the overall system
performance, and may possible cause a system lockup if you end up with a conflict
where the DMA cannot free the read bus as the read stall has prevented it writing
out its data due to some circular system relationship.
2. The Lite engine does not support 2D transfers. The TDMODE, S_STRIDE,
D_STRIDE and YLENGTH registers will all be removed. Setting these registers
will have no effect.
3. The DMA length register is now 16 bits, limiting the maximum transferrable length
to 65536 bytes.
4. Source ignore (SRC_IGNORE) and destination ignore (DEST_IGNORE) modes
are removed.
The Lite engine will have about half the bandwidth of a normal DMA engine, and are
intended for low bandwith peripheral servicing.