Re: Is there a binding for IORESOURCE_DMA population?

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Friday 15 July 2011 18:45:38 Tabi Timur-B04825 wrote:
> 
> On Fri, Jul 15, 2011 at 11:32 AM, Shawn Guo <shawn.guo-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:
> 
> > First of all, using powerpc dma-channel binding on such dma event
> > seems not reflecting the hardware facts.  Secondly, the binding in
> > this case (below) looks silly.  Thirdly, device driver need to make
> > code change for simply getting a dma event number.
> 
> Take a look at p1022ds.dts or mpc8610hpcd.dts.  We create separate DMA
> channel nodes on Freescale PowerPC parts because the channels really
> are independent.  On these two boards, some of the DMA channels are
> used by the async DMA driver, and two of the channels are used by the
> audio driver.

I think this is much better than using IORESOURCE_DMA fields, which
basically are only well-defined for PC-style i8237 DMA controllers
used in stuff like floppy drives and ISA sound cards.

However, we should find a way to standardize finding the dma_chan
for an platform_device based on a phandle. Maybe a little helper
that will scan a well-known property (dma-channels?) for phandles
to a device_node that is backing a struct dma_chan.

	Arnd