[PATCH V6 2/2] dmaengine: add helper function to request a slave DMA channel

Russell King - ARM Linux linux at arm.linux.org.uk
Tue Sep 18 14:10:39 EDT 2012

On Tue, Sep 18, 2012 at 03:20:08PM +0000, Arnd Bergmann wrote:
> On Tuesday 18 September 2012, Matt Porter wrote:
> > FWIW, I'm already basing the EDMA dmaengine support for OMAP (specifically
> > for AM335x) on using these helpers since AM335x only boots from DT.
> I suspect the same thing will be happening for a lot of platforms
> after 3.7-rc1: ux500, lpc32xx, integrator, imx, mxs and probably
> others are all waiting for this so they can complete the move
> to DT-only booting.

Integrator won't be, because no integrator platforms have DMA support.
That only came in with the Versatile range, of which it's extremely
dodgy and unreliable to use.  So in general, ARMs platforms do not have
working DMA support.

(I actually carry a private patch set which does enable full support on
Versatile platforms, but given the general brokenness of the platform I
see no reason to merge it and cause people issues with the platform when
they find out that DMA is broken in weird and wonderful ways depending
on the FPGA build they've happened to end up with...)

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