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

[Zhang Wei-r63237]

Hi, 

> -----Original Message-----
> From: Wood Scott-B07421 
> 
> 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
> variants?

I want to use this one driver to fit for mpc8349 and mpc8548. But it
seems some register difference between them.
Ok, using "fsl,mpc8548-dma".

> 
> > > +    - 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?
> 
It's clear, but maybe too long?

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

The basic mode could be used for mpc83xx silicons.

> 
> > > +    - 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
> channels.

DMA channels could be used as ethernet phy. You can point to DMA
channel's 'phandle' in the device node for reserve use.

> 
> 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.
> 

Your and my ideas are both sides of a coin. :-)

Thanks!
Wei.