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

From: Scott Wood <[email-masked]>
Date: Wed, 11 Jul 2007 10:23:52 -0500

Zhang Wei-r63237 wrote:
>>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.

Yes, and the 83xx device trees will list the compatible as 
fsl,mpc8349-dma, not fsl,mpc8548-dma.  This will tell the driver whether 
extended chain mode can be used (though I don't really see the benefit 
to using it even if it is there).

>>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. :-)

I think there's a substantive difference between them.  Making each 
channel an independent device makes it easier for other drivers to use them.

-Scott