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: Tue, 11 Jun 2013 17:08:45 -0600 Message-ID: <20130611230845.GB13892@obsidianresearch.com> References: <1370623671-7748-1-git-send-email-ezequiel.garcia@free-electrons.com> <20130609014506.GB10027@obsidianresearch.com> <20130611135737.GC3996@localhost> <20835253.Agl4DfuI3k@wuerfel> <20130611215023.GA12649@obsidianresearch.com> <51B7A325.8070108@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <51B7A325.8070108-Re5JQEeQqe8AvxtiuMwx3w@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: Sebastian Hesselbarth Cc: Lior Amsalem , Jason Cooper , Andrew Lunn , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Maen Suleiman , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Wed, Jun 12, 2013 at 12:22:29AM +0200, Sebastian Hesselbarth wrote: > sorry to kick into this thread that late but Ezequiel made me think of > address windows when asking on IRC. From what I can see from your and > Arnd's proposal the only real difference is that having it Arnd's way > allows you to have two or more windows mapped to e.g. devbus with > totally independent address ranges - while yours requires one large > window for all child devices? Sorry, I'm having problems following the possessives in your paragraph - which things are you comparing? > Although, not thought to the bare end this could also work and maybe > reflects the actual hardware more accuate: I actually posted something like this a time ago, but Arnd's suggestion to encode the target id in the address seems much clearer, and more accurate, though a bit more work to parse. It is 'better' in that the base addresses are in exactly one place - the ranges of the mbus node. With marvell,mbus-target the base addreses are strewn everywhere and now are difficult to change. A main consideration here is that the bootloader needs to update the base addresses - to support the 0xd0 vs 0xf1 internal-regs base address issue. So I think that requirement alone is enough to make marvell,mbus-target undesirable. > When removing size from marvell,mbus-target above, mbus driver could > also probe for required max size from the reg properties of the child > nodes. Arnd already said that mbus isn't "simple-bus" anymore, why > can't it just walk through the nodes and collect required windows? With enough restrictions, I think it is pretty easy to parse marvell,mbus-target, but you can employ the same restrictions to simplify parsing the 2 cell address format too. Jason