From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH 1/5] capemgr: Beaglebone DT overlay based cape manager Date: Tue, 8 Jan 2013 10:00:42 +0000 Message-ID: <20130108100042.GD21994@gmail.com> References: <1357584666-17374-1-git-send-email-panto@antoniou-consulting.com> <93BF5C62-ADE8-4EFC-9175-C2D7E43300E3@antoniou-consulting.com> <20130107210551.GL14149@atomide.com> <201301072135.05166.arnd@arndb.de> <89A7A8FD-935E-4225-8C7B-EA1DBA0C2780@antoniou-consulting.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <89A7A8FD-935E-4225-8C7B-EA1DBA0C2780@antoniou-consulting.com> Sender: linux-kernel-owner@vger.kernel.org To: Pantelis Antoniou Cc: Arnd Bergmann , Tony Lindgren , Grant Likely , Rob Herring , Rob Landley , Jon Loeliger , Stephen Warren , David Gibson , Benoit Cousson , Mitch Bradley , Alan Tull , Greg Kroah-Hartman , linux-omap@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Matt Porter , Russ Dill , Koen Kooi , Joel A Fernandes , Rob Clark , Jason Kridner , Matt Ranostay , Sascha Hauer , Linus Walleij List-Id: devicetree@vger.kernel.org > >>> At the end of the line, some kind of hardware glue is going to be= needed. > >>>=20 > >>> I just feel that drawing from a sample size of 1 (maybe 2 if I ge= t to throw > >>> in the beagleboard), it is a bit premature to think about making = it overly > >>> general, besides the part that are obviously part of the infrastr= ucture=20 > >>> (like the DT overlay stuff). > >>>=20 > >>> What I'm getting at, is that we need some user experience about t= his, before > >>> going away and creating structure out of possible misconception a= bout the uses.=20 > >>=20 > >> IMHO stuff like this will be needed by many SoCs. Some examples of= similar > >> things for omaps that have eventually become generic frameworks ha= ve been > >> the clock framework, USB OTG support, runtime PM, pinmux framework= and > >> so on. > >>=20 > >> So I suggest a minimal generic API from the start as that will mak= e things > >> a lot easier in the long run. > >=20 > > I agree. The ux500 platform already has the concept of "user interf= ace boards", > > which currently is not well integrated into devicetree. I believe S= ascha > > mentioned that Pengutronix had been shipping some other systems wit= h add-on > > boards and generating device tree binaries from source for each com= bination. > >=20 > > Ideally, both of the above should be able to use the same DT overla= y logic > > as BeagleBone, and I'm sure there are more of those. >=20 > Hmm, I see.=20 >=20 > I will need some more information about the interface of the 'user in= terface boards'. > I.e. how is the board identified, what is typically present on those = boards, etc. User Interface Boards are mearly removable PCBs which are interchangeab= le amongst various hardware platforms. They are connected via numerous connectors which carry all sorts of different data links; i2c, spi, rs2= 32, etc. The UIB I'm looking at right now has a touchscreen, speakers, a ke= y pad, leds, jumpers, switches and a bunch of sensors. You can find a small example of how we interface to these by viewing 'arch/arm/boot/dts/stuib.dtsi'. To add a UIB to a particular build, we currently include it as a *.dtsi from a platform's dts file. > Can we get some input by the owner of other similar hardware? I know = the FPGA > people have similar requirements for example. There are other people = that are hitting > problems getting DT to work with their systems, like the V4L people w= ith the order > of initialization; see http://lwn.net/Articles/531068/. I think the V= 4L problem is > cleanly solved by the overlay being contained in the V4L device node = and applied just before > the device is probed. >=20 > In the meantime it would be better to wait until we have some ack fro= m the maintainers > of the core subsystems about what they think. > =20 > Regards >=20 > -- Pantelis >=20 --=20 Lee Jones Linaro ST-Ericsson Landing Team Lead Linaro.org =E2=94=82 Open source software for ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog