Re: DMA_ENGINE: can't use it without selecting a dma engine driver

[Dan Williams <dan.j.williams@intel.com>]

Dragos Tatulea wrote:
> Hi,
> 
>>>        Just discovered that it's impossible to select the dma engine
>>> without compiling a dma engine driver from the kernel. What if I want to
>>> use a different dma engine?
>>>
>> Create a Kconfig entry for your driver in drivers/dma/Kconfig and have
>> it "select DMA_ENGINE".
> That's what I want to avoid. The dma engine driver is out of tree.
> 
> What is the rationale behind this? It seems (to me) impossible to have all
> such drivers in upstream.

It is very straightforward to have all drivers upstream, just send the 
code [1].

The rationale for this configuration scheme is to turn off a lot of 
unnecessary code when we know at build time that a dma driver will never 
be loaded.

If you must keep your driver out of tree simply maintain another out of 
tree patch that allows DMA_ENGINE to be manually enabled.

Regards,
Dan

[1]: http://www.kernel.org/doc/Documentation/SubmittingDrivers