Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758017Ab2EDVwh (ORCPT ); Fri, 4 May 2012 17:52:37 -0400 Received: from opensource.wolfsonmicro.com ([80.75.67.52]:45270 "EHLO opensource.wolfsonmicro.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752129Ab2EDVwf (ORCPT ); Fri, 4 May 2012 17:52:35 -0400 Date: Fri, 4 May 2012 22:52:30 +0100 From: Mark Brown To: Stephen Warren Cc: Arnd Bergmann , linux-arm-kernel@lists.infradead.org, Wolfgang Denk , Samuel Ortiz , linux-embedded@vger.kernel.org, Linus Walleij , linux-kernel@vger.kernel.org, Igor Grinberg , Olof Johansson , Lee Jones Subject: Re: Handling of modular boards Message-ID: <20120504215230.GS14230@opensource.wolfsonmicro.com> References: <20120504185850.GO14230@opensource.wolfsonmicro.com> <201205042039.25794.arnd@arndb.de> <20120504205441.D293120645E@gemini.denx.de> <201205042103.34285.arnd@arndb.de> <4FA4457F.1010900@wwwdotorg.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="LkYZvX65tyO4RZtj" Content-Disposition: inline In-Reply-To: <4FA4457F.1010900@wwwdotorg.org> X-Cookie: Advancement in position. User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2777 Lines: 67 --LkYZvX65tyO4RZtj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, May 04, 2012 at 03:09:19PM -0600, Stephen Warren wrote: > On 05/04/2012 03:03 PM, Arnd Bergmann wrote: > > Sure, there are a lot of things that the boot loader can use from the > > device tree, but I'm not sure if the LCD panel connection fits into > > the same category as the devices that Mark was thinking of. > A board I have sitting on my desk right now has separate boards for (and > multiple options for each of): > * Motherboard > * CPU+DRAM > * PMU/PMIC > * Display (LCD) > ... and many more. > Interaction with the PMU/PMIC is required for at least some of the boot > media options. Yeah, similar setup for our boards except the PMICs are soldered down onto other boards. We've got a mainboard, three audio boards of various kinds, a random non-audio components board and a CPU/DRAM board. There's good solid engineering reasons for doing this. CPUs and RAMs tend to be very high density devices with lots of pins and be difficult enough to route to require large numbers of layers (and ideally you want the PMIC to be physically close to them since long traces tend to become electrically interesting for CPU style loads, especially when routed through connectors) all of which leads to an expensive board which you pay for by area. With reference boards with large form factors it's worth the effort to have a separate, smaller, board manufactured to meet these requirements - even in very low volumes the cost wins are noticable. --LkYZvX65tyO4RZtj Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJPpE+VAAoJEBus8iNuMP3dFoQQAJLhLauyyrv0tqZ/07cMNMa4 zREYjnCc9V43IZkja7225fUxgvBdbGcCbLy0pPnEhRFa2CjeJkxTM193abzKF9LO gw2+RoKwAQeP6Jl9lZk+XUnN/4yE6VrriDC8vDCa1bEikBwRzq7jRrq5i9xglxG5 tUsWmv6cdMUkQNf5OzYqFUDvuZb8qEIf2JKkjmPp6utOquC7kqPgkGvnTbioBL9X BhjackNDA5uo1J8hq6m0Pxxplx+usKuPHbEiOyx52G1QSXzhIeEPdnpwACYgIkdb srNS+sgs8ZkpsahytYogsfkvnybJd1QILmG0Bt58pfcF1yRmJl2b13qLW+BaNSJG gXbdf/0ZaHdvy9OMpQdzBsU9QptR9tvL+jKCG4u0LeVUNhXdyVJoaJqkoYmaF+ad DlCFhAPBVppUmvHFfZKc21gPsY3UMDLDuUNZ/957daU6mXenEt9+aGSj4/j70ugo 4EqHf8YD81xfqGTQWrmxZwDM64FOXYjXjhcHBGTSvrgCCqMMMxz3VBvC9JYkxhnz WLReRih9FfHz4dKysIO1cgV0Rudoce7uC9gQr2cSO7vIc++okSJEOQIDh8utRbgp 3XjZdSi2JIPHQ+Zd36Gx562GjJlGTEn7WQZctFSR9XBJT5sY8K01qmaJWsca8ooM VNWpIbeLEeva8eaE0+3+ =7/jL -----END PGP SIGNATURE----- --LkYZvX65tyO4RZtj-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/