[PATCH V4 1/5] ARM: add infra-structure for BCM2835 and Raspberry Pi

On 09/14/2012 01:50 AM, Arnd Bergmann wrote:

On Friday 14 September 2012, Stephen Warren wrote:

quoted

From: Simon Arlott <redacted>

The BCM2835 is an ARM SoC from Broadcom. This patch adds very basic
support for this SoC.

http://www.broadcom.com/products/BCM2835
http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pd

Just looked at that document. Funny how they actually put details about
the kernel implementation (the static mapping address) into a hardware
manual.

Yes. I keep hoping they'll fix this and re-issue the document. Dom, what
do you think that chances are of that?

quoted

Note that the documentation in the latter .pdf assumes the MMU setup
that's used on the "VideoCore" companion processor, and does not document
physical peripheral addresses. Subtract 0x5e000000 to obtain the physical
addresses.

This had escaped me so far. I think we should put this into the device tree
so that the representation of devices in the .dts file matches the one in
the manual, like this

	vc-bus {
		compatible = "simple-bus";
		#address-cells = <1>;
		#size-cells = <1>;
		ranges = <0x20000000 0x7e000000 0x02000000>;

		other devices {

		};
	};

I guess I can see the advantage of having the .dts reg values match the
documentation. I just worry that doing so is more about matching the
documentation rather than describing the true HW. Still, I suppose with
the ranges property, it's clear what the true physical addresses are..
It also introduces a completely fake bus just to perform the address
re-writing; I wonder if putting the ranges property at the top-level
node work instead?.

So  now that almost everything is ack'd, how should this get into the
tree - will you take (an updated version of) these patches and apply
them directly to arm-soc, or should I commit them and send a pull
request? (For the latter, I'd have to look up how to create a new k.org
git repo).

Thanks for the reviews.