Thank Scott and Timur!
Scott Wood wrote:
Timur Tabi (CCed) has written an audio
driver that does something very similar; he could probably tell you more
about how to do that (this is why such discussions should be kept on the
mailing list rather than taken to private e-mail).
The code in drivers/dma cannot be used to send a buffer of data to a
single I/O port. That code is just an elaborate version of memcpy that
uses the DMA engine to copy data in the background.
Thanks for your explaination! So if I want to transfer a buffer of data
from a single I/O port, will not DMA framework
also be able ? Have I to write aother driver?
If you want to transfer a buffer to a single I/O port, you will need to
write your own DMA driver, similar to what I've done in
sound/soc/fsl/fsl_dma.c. This is not trivial. You will need to
understand the DMA hardware programming model to determine whether you
can use direct mode or if you need to create link descriptors.
Actually, I don't want write all because there are serveral DMA code at
hand. I only want to use a framework instead of re-writing.
And I afraid that I can not write code which assure sharing DMA channels.
Regards!
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