[PATCH] ARM:SAMSUNG: Move S3C DMA driver to drivers/dma

Russell King - ARM Linux linux at arm.linux.org.uk
Wed Jun 8 03:44:11 EDT 2011

On Wed, Jun 08, 2011 at 09:35:34AM +0530, Jassi Brar wrote:
> In real life, I saw that with the Samsung's SPDIF controller which has
> fifo depth only for a few samples and it gets very demanding if pro
> quality is expected. Aggravate that with high irq-latency under system
> load.
> And in such cases, it is much more preferable to employ system timers
> to generate period_elapsed updates and queue the whole ring buffer as
> one transfer item to be iterated endlessly by dma. Ex, PL330 doesn't
> lend to LLI but can be programmed endlessly looping one transfer item.

So you're talking about the _hardware_ circular buffer case which I
mentioned in my email.  No problem with the DMA engine API as has
already been said - it supports preparation of circular buffers.

So, from everything discussed so far, there's nothing lacking from
the DMA engine API for your purposes.

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