Hi,
On Fri, Nov 20, 2009 at 04:04:32PM +0100, ext Sergei Shtylyov wrote:
Hum... does Mentor DMA indeed not interrupt on a receiving a short
packet? Ah, that must be a consequence of using DMA mode 1... hm, need to
study the current code more WRT CPPI...
it's consequence of mode 1, yes.
When in mode 1, you don't get an irq for the last short packet and the
dma engine doesn't transfer that. Instead, you'll get an endpoint irq
and you have to either reprogram dma for mode0 or use pio.
We chose pio as it seemed simpler and enough. I mean, you only have
<512-byte packet to receive and you already got an ep irq, if you
reprogram mode0 dma, you'll have to wait dma to take ownership of the
AHB and you'll get another irq (now for dma completion).
Ah... the current CPPI code only uses Rx DMA mode 0, and so but you're
changing that to always use mode 1... nevermind then, I just didn't know
well how that mode works.
yes, the idea is to remove support for mode0 and the code a lot simpler.
We will support mode1 dma and pio, only. See above the rationale on it.
what do you (all) think ??
--
balbi
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