Subject: [PATCH v6 3/4] drivers: of: add initialization code for dma reserved memory

From: [email-masked] (Stephen Warren)
Date: Mon, 19 Aug 2013 15:49:20 -0600

On 08/19/2013 09:04 AM, Marek Szyprowski wrote:
> This patch adds device tree support for contiguous and reserved memory
> regions defined in device tree.

> diff --git a/Documentation/devicetree/bindings/memory.txt b/Documentation/devicetree/bindings/memory.txt

> +*** Reserved memory regions ***
> +
> +In /memory/reserved-memory node one can create additional nodes

s/additional/child/ or s/additional/sub/ would make it clearer where the
"additional" nodes should be placed.

> +compatible:	"linux,contiguous-memory-region" - enables binding of this
> +		region to Contiguous Memory Allocator (special region for
> +		contiguous memory allocations, shared with movable system
> +		memory, Linux kernel-specific), alternatively if
> +		"reserved-memory-region" - compatibility is defined, given
> +		region is assigned for exclusive usage for by the respective
> +		devices

"alternatively" makes it sound like the two compatible values are
mutually-exclusive. Perhaps make this a list, like:

----------
compatible: One or more of:

	- "linux,contiguous-memory-region" - enables binding of this
	  region to Contiguous Memory Allocator (special region for
	  contiguous memory allocations, shared with movable system
	  memory, Linux kernel-specific).
	- "reserved-memory-region" - compatibility is defined, given
	  region is assigned for exclusive usage for by the respective
	  devices.
----------

"linux,contiguous-memory-region" is already long enough, but I'd
slightly bikeshed towards "linux,contiguous-memory-allocator-region", or
perhaps "linux,cma-region" since it's not really describing whether the
memory is contiguous (at the level of /memory, each chunk of memory is
contiguous...)

> +*** Device node's properties ***
> +
> +Once regions in the /memory/reserved-memory node have been defined, they
> +can be assigned to device nodes to enable respective device drivers to
> +access them. The following properties are defined:
> +
> +memory-region = <&phandle_to_defined_region>;

I think the naming of that property should more obviously match this
binding and/or compatible value; perhaps cma-region or
contiguous-memory-region?