Subject: [PATCH 0/2] Revert support for reserved memory regions defined in device tree

From: [email-masked] (Marek Szyprowski)
Date: Tue, 19 Nov 2013 13:27:53 +0100

Hi Grant!

On 2013-10-30 14:47, Grant Likely wrote:
> On Fri, 11 Oct 2013 09:27:26 +0200, Marek Szyprowski<[email-masked]>  wrote:
> > Hi all!
> >
> > Benjamin Herrenschmidt pointed a few issues in the proposed design of
> > device tree bindings for contiguous memory allocator and reserved memory
> > regions:
> >https://lkml.org/lkml/2013/9/15/151
> >http://www.spinics.net/lists/arm-kernel/msg273548.html
> >
> > Some time has passed, but there is still no consensus on the bindings
> > for the reserved memory and various drawback of this solution has been
> > shown, so in my opinion the best I can do now is to revert them
> > completely and start from scratch again later.
>
> Hi Marek,
>
> At the ARM summit last week in Edinburgh, several of us sat down and
> hammered out a new proposal for handling reserved memory regions based
> on the work that you started here. Below you will find a new binding
> document. I started looking at implementing this, but haven't made much
> progress.
>
> Please take a look and let me know what you think.
>
> Also, while I'm thinking about it, I took another look at the code and I
> think the code supporting reserved regions should go directly into
> drivers/of/fdt.c and drivers/of/memory.c.  Also, the reserved regions
> parsing should be enabled unconditionally insted of filtered by (DMA_CMA
> || (HAVE_GENERIC_DMA_COHERENT && HAVE_MEMBLOCK). If the hardware
> description says to reserve a region, then the kernel must always do so,
> even if it doesn't actually use it for anything.

Thanks for discussing this item. I'm really sorry for the late reply, but
various 'more_imporant_things(tm)' have eaten me completely last weeks.

The proposal look good for me. I'm not convinced that we really need the
support for 'reg' property, as the fixed memory region is a special case
of generic dynamic allocation specified by the size and alloc-ranges, but
I assume that there have been already a long discussion about this, so I
accept the common consensus.

Grant: have you started working on the code, which implements such binding?
If not, I will try to start do it and post the code soon for review.

Best regards
-- 
Marek Szyprowski
Samsung R&D Institute Poland