[PATCH] DMA: mv_xor: Add a device_control function

[Andrew Lunn]

On Sat, Nov 17, 2012 at 06:15:01PM +0100, Andrew Lunn wrote:
> The dmatest module for DMA engines calls
> 
> device_control(dtc->chan, DMA_TERMINATE_ALL, 0);
> 
> after completing the tests. The documentation in
> include/linux/dmaengine.h suggests this function is optional and
> dma_async_device_register() also does not BUG_ON() when not passed a
> function. However, dmatest is not the only code in the kernel
> unconditionally calling device_control. So add an implementation
> indicating all operations are not implemented.
> 
> Signed-off-by: Andrew Lunn <andrew at lunn.ch>

Arg!

Sorry, please ignore this version. I should not be removing length checks.

       Andrew