[PATCH 1/4] Add DMA sector to Documentation/powerpc/booting-without-of.txt file.

Scott Wood scottwood at freescale.com
Wed Jul 11 02:11:21 EST 2007

On Tue, Jul 10, 2007 at 04:01:19PM +0200, Segher Boessenkool wrote:
> > +    - compatible : Should be "fsl,mpc8xxx-dma"
> Should _include_, not should _be_.  And none of this xxx
> business, of course.

Especially since the 85xx/86xx version is not 100% compatible with the
83xx version.  How about fsl,mpc8349-dma and fsl,mpc8548-dma for the two

> > +    - extended : Set the DMA channel to work at extended chain mode.
> > +                 If not set, the DMA channel will work at basic
> > +                 chain mode.
> Call it "extended-chain-mode", perhaps?

Or don't call it anything.  The ability to do extended chain mode is
implicit in being compatible with fsl,mpc8548-dma.

> > +    - reserved : Reserve the DMA channel to device.
> What does this do?  Reserve it for what device, and where?
> The OS driver?

Some hardware has DMA channels hardwired to certain peripherals, such as
an audio codec.  This keeps them from being used as general purpose DMA

I'd rather just treat the different DMA channels as independent devices,
rather than children of a dma "bus", and change the compatible name if
they're not general purpose.  There's only one register that's shared
among the channels, and it's a superfluous status summary register.


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