Re: [RFC PATCH 4/4] ARM: Xilinx: Adding Xilinx board support

Grant Likely
2011-05-02T23:36:25Z

On Mon, May 2, 2011 at 5:01 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Mon, May 02, 2011 at 09:50:11PM +0000, johnlinn@comcast.net wrote:
>> Seems easy enough assuming we don't need the SCU early for the core count
>> and can get that from the device tree.
>
> Beware.  Things may not be that trivial when you start considering some
> of the weirdnesses that some vendors start coming out with.
>
>> Since the SCU and part of the GIC end up in the same 4K page they need to be
>> together (unless I'm thinking about that wrong).
>>
>> SCU 0xF8000000
>> GIC_CPU 0xF8000100
>> GIC_DIS 0xF8001000
>
> It is preferable to use the same mapping, as it ensures that you're not
> going to create incompatible aliases.
>
> But, before we get too bogged down with this, please realise that it is
> possible to setup early mappings from the device tree for things like the
> SCU.  Maybe not using ioremap(), but I'm sure we can find some way to use
> the iotable_init() stuff to setup some early mappings from DT for this
> stuff.

absolutely.

g.