On Tue, 19 Nov 2013 13:27:53 +0100, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: > Hi Grant! > > On 2013-10-30 14:47, Grant Likely wrote: > > On Fri, 11 Oct 2013 09:27:26 +0200, Marek Szyprowski<m.szyprowski@xxxxxxxxxxx> 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. It is absolutely necessary for some use cases. For example, a framebuffer enabled by firmware and passed onto the kernel for flicker-free boot. Some platforms have fixed regions that cannot be moved up. > 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. No, please go ahead and start. g. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
