From mboxrd@z Thu Jan 1 00:00:00 1970 From: jgunthorpe@obsidianresearch.com (Jason Gunthorpe) Date: Wed, 12 Jun 2013 16:02:50 -0600 Subject: [PATCH 04/14] bus: mvebu-mbus: Add static window allocation to the DT binding In-Reply-To: <201306122352.32749.arnd@arndb.de> References: <1370623671-7748-1-git-send-email-ezequiel.garcia@free-electrons.com> <20130612212641.GB8625@obsidianresearch.com> <20130612213620.GC23012@localhost> <201306122352.32749.arnd@arndb.de> Message-ID: <20130612220250.GA14852@obsidianresearch.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jun 12, 2013 at 11:52:32PM +0200, Arnd Bergmann wrote: > Whether that results in an optimum mapping or not depends on the actual > sizes for the child nodes. Since everything is a power-of-two size, > a first-fit algorithm actually isn't bad at all. The windows must be aligned to their size. eg 1M size window must be aligned to a 1M boundary. First fit only works if you allocate from largest alignment requirement to smallest, otherwise the worst case is something like nearly double the largest alignment wasted in alignment padding. Jason From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH 04/14] bus: mvebu-mbus: Add static window allocation to the DT binding Date: Wed, 12 Jun 2013 16:02:50 -0600 Message-ID: <20130612220250.GA14852@obsidianresearch.com> References: <1370623671-7748-1-git-send-email-ezequiel.garcia@free-electrons.com> <20130612212641.GB8625@obsidianresearch.com> <20130612213620.GC23012@localhost> <201306122352.32749.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <201306122352.32749.arnd-r2nGTMty4D4@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Arnd Bergmann Cc: Lior Amsalem , Andrew Lunn , Jason Cooper , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Maen Suleiman , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Sebastian Hesselbarth List-Id: devicetree@vger.kernel.org On Wed, Jun 12, 2013 at 11:52:32PM +0200, Arnd Bergmann wrote: > Whether that results in an optimum mapping or not depends on the actual > sizes for the child nodes. Since everything is a power-of-two size, > a first-fit algorithm actually isn't bad at all. The windows must be aligned to their size. eg 1M size window must be aligned to a 1M boundary. First fit only works if you allocate from largest alignment requirement to smallest, otherwise the worst case is something like nearly double the largest alignment wasted in alignment padding. Jason