[PATCH] Documentation: dmaengine: Add a documentation for the dma controller API

[lars@metafoo.de (Lars-Peter Clausen)]

On 07/31/2014 07:37 PM, Maxime Ripard wrote:
> On Thu, Jul 31, 2014 at 06:54:11PM +0200, Lars-Peter Clausen wrote:
>> On 07/31/2014 06:13 PM, Maxime Ripard wrote:
>> [...]
>>>  From what you're saying, and judging from the drivers that already
>>> implement it, can't it be moved directly to the framework itself ?
>>>
>>
>> What exactly do you mean by moving it directly to the framework? The
>> slave_caps API is part of the DMAengine framework.
>
> Not its implementation, which is defined by each and every driver,
> while the behaviour of device_slave_caps is rather generic.
>

Do you mean something like adding a dma_slave_caps struct field to the DMA 
channel that gets initialized when the channel is created and then remove 
the callback? That makes some sense.

I think the main reason why we use a callback right now is that in earlier 
revisions of the API it was possible to pass a slave_config and the result 
would be the capabilities of the DMA channel for this particular config. But 
this was dropped before the final version was merged upstream.

- Lars