From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from saturn.retrosnub.co.uk ([178.18.118.26]:35281 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751356AbcCOV4Q (ORCPT ); Tue, 15 Mar 2016 17:56:16 -0400 Subject: Re: [PATCH v2 4/5] iio:magnetometer:ak8975: mounting matrix support To: Gregor Boirie , linux-iio@vger.kernel.org References: <022da3dfc0853c6f9820b24c2d9eaaf0c5ccf294.1457001111.git.gregor.boirie@parrot.com> <56DAFCEB.6080905@kernel.org> <56E0014D.1040209@parrot.com> <56E08B91.6070603@kernel.org> <56E6F2BA.5010101@parrot.com> From: Jonathan Cameron Message-ID: <56E884FE.90005@kernel.org> Date: Tue, 15 Mar 2016 21:56:14 +0000 MIME-Version: 1.0 In-Reply-To: <56E6F2BA.5010101@parrot.com> Content-Type: text/plain; charset=windows-1252 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 14/03/16 17:19, Gregor Boirie wrote: > On 03/09/2016 09:46 PM, Jonathan Cameron wrote: > > [snip...] >> Definitely needs ABI docs in Documentation/ABI/testing/sysfs-bus-iio >> as well. We need the reference directions to be well specified as >> well - how do we define the main hardware orientation? on yours presumably >> the usual approach of using the screen is irrelevant so that definition >> could be a little 'interesting' to write down? >>> The standard orientation for us is defined with respect to the drone's head >>> and the propellers plane, which does not suit the nominal use cases indeed... >>> Although it really deserves some more detailed documentation, I wonder if the >>> question is relevant. >>> Given that the DTS is board specific (correct me if I'm wrong), why not >>> consider the reference orientation as board specific as well (and make the >>> whole thing implicit) ? >> I think that is fine for your sort of usecase - though might be nice to keep >> a bit of documentation somewhere (perhaps as comments in the DTS), or perhaps >> more centrally - would be nice for userspace libraries if at least all aircraft >> had a similar 'default orientation'. > As you said earlier, things are never that simple. The standard orientation > may vary with types of UAVs (quad-rotor, fixed wings, bizarre home made UFOs...) Sure, but let's document what we can so at least some cases are covered >> For the more 'standard' device with a screen I think we would want to standardise >> if at all possible. Most hand held devices have a 'natural' orientation >> (front facing camera at the top for example). In those cases we are basically looking >> at whether the sensor is mounted on the back or the front of the main circuit board and >> then of course it can be at any rotation in plane but typically is at 90 degrees >> (hence the inv mpu limitations) >> >> I'm guessing there are existing userspace mappings for this. Perhaps in the Gnome >> sensors stuff? > [snip...] > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html