From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Figa Subject: Re: [PATCH v2 1/5] drivers: of: add initialization code for reserved memory Date: Tue, 11 Feb 2014 21:27:36 +0100 Message-ID: <52FA87B8.8040203@gmail.com> References: <1391515773-6112-1-git-send-email-m.szyprowski@samsung.com> <1391515773-6112-2-git-send-email-m.szyprowski@samsung.com> <20140205110538.99E47C40A89@trevor.secretlab.ca> <52FA0D6E.9090304@samsung.com> <20140211121316.24032C40C4D@trevor.secretlab.ca> <52FA33E2.4050004@samsung.com> <20140211190104.7E6C5C4140E@trevor.secretlab.ca> <1392148971.3835.15.camel@pasglop> <52FA8245.5050707@gmail.com> <20140211201933.GI841@joshc.qualcomm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140211201933.GI841@joshc.qualcomm.com> Sender: linux-kernel-owner@vger.kernel.org To: Josh Cartwright Cc: Benjamin Herrenschmidt , Grant Likely , Tomasz Figa , Marek Szyprowski , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linaro-mm-sig@lists.linaro.org, devicetree@vger.kernel.org, linux-doc@vger.kernel.org, Kyungmin Park , Arnd Bergmann , Michal Nazarewicz , Sascha Hauer , Laura Abbott , Rob Herring , Olof Johansson , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Kumar Gala , Nishanth Peethambaran , Marc List-Id: devicetree@vger.kernel.org On 11.02.2014 21:19, Josh Cartwright wrote: > On Tue, Feb 11, 2014 at 09:04:21PM +0100, Tomasz Figa wrote: >> >> >> On 11.02.2014 21:02, Benjamin Herrenschmidt wrote: >>> On Tue, 2014-02-11 at 19:01 +0000, Grant Likely wrote: >>> >>>>> 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@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