Re: [PATCH] dmaengine: add dma_ctrl_cmd to pass buffer stride configuration

From: Jassi Brar
Date: Sat Jul 23 2011 - 16:35:39 EST

On Mon, Jul 18, 2011 at 1:21 PM, Raju, Sundaram <sundaram@xxxxxx> wrote:
>> Maybe a new api to pass fixed-format variable-length encoded message
>> to the DMAC drivers?
>> Which could be interpreted by DMAC drivers to extract all the needed xfer
>> parameters from the 'header' section and instructions to program the xfers
>> in the DMAC from the variable length body of the 'message' buffer.
>> It might sound complicated but we can have helpers to make the job easy.
>> Btw, the regular single/sg-list xfers could also be expressed by this method.
> Do you expect this variable length body of the message to be DMAC
> independent? I don't think so. In that case how is this different from what
> we have here already?
Yes, this whould be DMAC independent.

> If it can be DMAC independent, can you illustrate more on how this can
> be done? But the point to note is, if this can be made DMAC independent
> then the control command we have also can be made DMAC independent
> by generalizing the configuration structure passed to it.
The 'header' I suggest, would in fact be a structure body, only an extra pointer
would point to the 'instructions' to convey actual location and sizes
of mico-xfers.
I don't think it is possible to have general definition of such transfers fully
within a structure. If I understand what you ask.

I have just posted an RFC. I kept the terms same so that it is easier
to understand.
Please have a look. You are CC'ed too.

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