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

From: Dan Williams
Date: Wed Jun 17 2009 - 12:38:42 EST

Dragos Tatulea wrote:

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.



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