> -----Original Message-----
> From: Tim Waugh [mailto:twaugh@redhat.com]
> Sent: Monday, March 20, 2000 1:49 PM
> To: Chandan Mishra
> Cc: linux-parport@torque.net
> Subject: Re: DMA channel configuration
>
>
> On Mon, 20 Mar 2000, Chandan Mishra wrote:
>
> > I have a question which is not parallel port specific but
> arose during
> > the time while I was playing with parport driver. On PC how
> is the dma
> > channel autoconfigured if it is. As my understanding goes each
> > peripherical controller is kind of hard wired to a particular dma
> > channel of a dma controller (corect me if I am wrong). Then how does
> > auto configuration works or how odes the driver discover the dma
> > channel to use. Also how does peripheral auto-finds the available
> > irqs.
>
> For parallel ports: ECP chipsets just tell you this
> information. You ask
> the chipset what DMA channel and IRQ line it's using, and it
> tells you.
> It's theoretically possible to program it to use a DMA channel and IRQ
> line of your choice, but I've never seen an implementation that allows
> that.
>
> For IRQs, see probe_irq_on and probe_irq_off.
>
Well how can ECP chipsets discover which dma channel they should use. I mean
isnt it set by jumpers or so, I mean isnt it hardwired. Can there be dynamic
allocation dma channel. I mean if I am a peripheral controller, is it
poosible for me to use one dma channel at one time and another at another
time. Arent the dma channel already hardcoded on the board I mean in the way
the connection from peripheral controller to hardware is.
Please clarify for me. I know its kind of general pc hardware kind of
question but I thought someone here might answer me.
> Tim.
> */
>
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