[PATCH 4/6] DMA: PL330: Add device tree support

Thomas Abraham thomas.abraham at linaro.org
Tue Aug 30 22:21:17 EST 2011


Hi Russell,

On 26 August 2011 19:53, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
>
> On Fri, Aug 26, 2011 at 08:16:11AM -0500, Rob Herring wrote:
> > Thomas,
> >
> > On 08/26/2011 03:40 AM, Thomas Abraham wrote:
> > > +  - arm,pl330-peri-reqs: number of actual peripheral requests connected to the
> > > +    dma controller. Maximum value is 32.
> >
> > Perhaps could be a bitmask for sparsely populated requests. May not
> > matter since phandles will define the connections.
> >
> > Can be optional and not present means 00 requests (mem-to-mem only).
>
> The number of peripheral requests is readable from configuration register
> zero, so this is discoverable.  Why should we put this information into
> DT if its provided by the hardware?
>
> The number of DMA channels available is also configurable by the SoC
> designer, yet you don't specify that in DT.  And there's a whole bunch
> of other configuration options available to the SoC designer, most of
> which are discoverable from the configuration registers.
>
> So, I don't think you should be specifying the number of requests.

Ok. The property specifying the number of peripheral requests will be dropped.

Thanks,
Thomas.


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