[PATCH 1/4] Add DMA sector to Documentation/powerpc/booting-without-of.txt file.
Wei.Zhang at freescale.com
Wed Jul 11 20:00:07 EST 2007
> -----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
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
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. :-)
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