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

Arnd Bergmann
2011-05-03T10:36:02Z

On Tuesday 03 May 2011, Russell King - ARM Linux wrote:
> On Tue, May 03, 2011 at 09:58:14AM +0200, Arnd Bergmann wrote:
> > On Tuesday 03 May 2011 01:01:18 Russell King - ARM Linux wrote:
> > > It is preferable to use the same mapping, as it ensures that you're not
> > > going to create incompatible aliases.
> >
> > Is aliasing a problem for MMIO mappings? I would think that you can
> > ioremap registers anywhere and as often as you want because they are
> > never cacheable.
>
> Provided the type and sharability is identical then there is no problem.
> I wasn't referring to multiple ioremap()s of the same region - that
> should be fine as the same attributes will be used. If you mix ioremap()
> and iotable_init() then you _could_ have problems if you don't use
> MT_DEVICE in the iotable.
>
> What I'm basically saying is that mixing the methods of creating these
> mappings makes it much easier to get tripped up over these issues.

Ok, makes sense.

Thanks,

Arnd