From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Dooks Subject: Re: Handling of modular boards Date: Thu, 10 May 2012 11:43:11 +0100 Message-ID: <20120510104311.GB30103@trinity.fluff.org> References: <20120504185850.GO14230@opensource.wolfsonmicro.com> <4FA432E9.9050606@wwwdotorg.org> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <4FA432E9.9050606@wwwdotorg.org> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Stephen Warren Cc: Mark Brown , Samuel Ortiz , linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org, Igor Grinberg , Olof Johansson , Arnd Bergmann , linux-arm-kernel@lists.infradead.org On Fri, May 04, 2012 at 01:50:01PM -0600, Stephen Warren wrote: > On 05/04/2012 12:58 PM, Mark Brown wrote: > > Quite a few reference platforms (including Wolfson ones, which is why > > I'm particularly interested) use replaceable modules to allow > > configuration changes. Since we can often identify the configuration at > > runtime we should ideally do that but currently there's no infrastructure > > to help with that... > > So, I'll respond within the context of device tree, although perhaps you > were looking for something more general? > > I was just asked basically the same question internally to NVIDIA. One > option that was floated was to store the device tree in chunks and have > the bootloader piece them together. You'd start with the DT for the > basic CPU board, probe what HW was available, and then graft in the > content of additional DT chunks and pass the final result to the kernel. > The advantages here are: > > a) The DT is stored in chunks for each plugin board, so there's no bloat > in the DT that gets passed to the kernel; it contains exactly what's on > the board. Interesting, but how does it sort ofu things like mapping GPIO lines from the add-in board's view to the rest of the system? -- Ben Dooks, ben@fluff.org, http://www.fluff.org/ben/ Large Hadron Colada: A large Pina Colada that makes the universe disappear.