On Wed, 2012-01-25 at 18:41 +0530, Ravi Kumar V wrote:

On 1/23/2012 7:21 PM, Vinod Koul wrote:

quoted

On Mon, 2012-01-23 at 16:41 +0530, Ravi Kumar V wrote:

quoted

If some changes are made in interleave API then it can support our BOX
mode. Here in interleaved template he is assuming destination pattern as
can be contiguous or same as source pattern, but in our case destination
pattern is different from source pattern.
So if a new parameter destination data chunk is added in "struct
dma_interleaved_template" structure then it can support different
destination pattern.

do you mean you have cases where you are doing a "memcpy" from one
interleaved memory to another?
Can you provide me with a scenario where this maybe helpful?

Presently we are transferring data from interleaved memory tho 
contagious memory and vice-verse.
We can use the interleaved API for present scenario, but it will 
restrict the HW capability of transferring data from one interleaved 
pattern to other interleaved pattern.

That's interesting capability.
My question still unanswered is whats the real work usage of this
capability. Helps to understand what this would be used for and
providing optimal solution

quoted

The reason why the API was designed like this was to give ability to
take these kind of interleaved memory and copy them to peripheral
(constant addr) or memory (typically contagious).

In case it is just a pattern I wonder why it cannot be described in
standard scatter gather definitions as you can split the block further
down to copy from one respective block to somewhere else in memory.

We can use scatter gather but it will be extra burden on software to 
create those many SG list unlike in box mode just a single command 
serves the purpose.

quoted

quoted

Also it will good if you can provide another parameter for passing
private data to dma driver.

1. what does this parameter do?

Private parameter in our case will be command configuration parameter 
where we are passing information to HW like endianness, synchronization 
& acknowledge mechanism between DMA HW and peripherals running with 
different clock than DMA.

This is a separate discussion. We had similar talk on need to pass
controller/subsystem specific parameters [1] sometime back during RIO
patches. Alexandre has posted a new RFC [2] which should be extended to
whatever API you finally end up using

[1]: https://lkml.org/lkml/2011/10/24/275 
[2]: https://lkml.org/lkml/2012/1/26/405

-- 
~Vinod