On 11.02.2014 21:19, Josh Cartwright wrote:

On Tue, Feb 11, 2014 at 09:04:21PM +0100, Tomasz Figa wrote:

quoted

On 11.02.2014 21:02, Benjamin Herrenschmidt wrote:

quoted

On Tue, 2014-02-11 at 19:01 +0000, Grant Likely wrote:

quoted

quoted

except that the former IMHO better suits the definition of memory
region, which I see as a single contiguous range of memory and can be
simplified to have a single reg entry per region.

My point is rather if multiple reg tuples are found in a reserved memory
node, the kernel must respect them and reserve the memory. I'm not
arguing about whether or not that makes for a good binding.

agreed.

My point is why, if the binding defines that just a single tuple should be
provided.

FWIW, the usecase I had mentioned in reply to Grant in the patch 5/5
thread [1] could make use of this.  The shared memory region is split
into a main chunk and several "auxiliary" chunk, but collectively these
regions all share the same heap state.

   Josh

1: http://lkml.kernel.org/r/20140205192502.GO20228 at joshc.qualcomm.com

The use case seems fine, but I believe it could be properly represented 
in device tree using multiple single-reg regions as well, unless the 
consumer can request a block of memory that crosses boundary of two 
sub-regions specified by reg entries of single region.

Best regards,
Tomasz