From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755150AbbAOOjM (ORCPT ); Thu, 15 Jan 2015 09:39:12 -0500 Received: from mail.kernel.org ([198.145.29.136]:53280 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631AbbAOOjJ convert rfc822-to-8bit (ORCPT ); Thu, 15 Jan 2015 09:39:09 -0500 Date: Thu, 15 Jan 2015 15:38:55 +0100 From: Sebastian Reichel To: "Dr. H. Nikolaus Schaller" Cc: Dmitry Torokhov , Belisko Marek , Rob Herring , Pawel Moll , Mark Rutland , "ijc+devicetree@hellion.org.uk" , Kumar Gala , Benoit Cousson , Tony Lindgren , Russell King - ARM Linux , "devicetree@vger.kernel.org" , LKML , "linux-omap@vger.kernel.org" , linux-arm-kernel , linux-input@vger.kernel.org, Marek Belisko , Jonathan Richardson , Scott Branden , Yoichi Yuasa , Maxime Ripard , List for communicating with real GTA04 owners Subject: Re: [PATCH 1/3] input: tsc2007: Add pre-calibration, flipping and rotation Message-ID: <20150115143855.GD512@earth.universe> References: <1412108254-19234-1-git-send-email-marek@goldelico.com> <1412108254-19234-2-git-send-email-marek@goldelico.com> <20150115005938.GB9134@dtor-ws> <0F9A17C1-9B01-4EE9-BE98-266B8FC02B84@goldelico.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <0F9A17C1-9B01-4EE9-BE98-266B8FC02B84@goldelico.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Jan 15, 2015 at 08:36:44AM +0100, Dr. H. Nikolaus Schaller wrote: > > 1. Perform conversion in input core rather than individual drivers. I > > think we should allocate a new bitmaps for some transformations and have > > the code do X/Y flip/clip of the coordinates. > > Do you have a suggestion where this should be (I have no clue how > the input system works or is structured - we just know how to extend a > driver that uses it)? > > > 2. Standardize on bindings. We already have of-touchscreen.c doing > > rudimentary parsing, we shoudl look into extending it rather than > > creating myriad of driver-specific bindings. > > Ok, looks reasonable. Documentation is in Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt > > Also, do we need swap and flip or do we simply need rotation (like the > > proposed Broadcom iproc driver has)? > > Well, since the DT should describe hardware, there are 3 sets of wires which > can have a cross-over: X+ and X-, Y+ and Y-, X and Y. > > So IMHO hardware has no “rotation”, just crossover of wires. Rotation is an > interpretation of the result of these connections in combination with some > panel the touch is glued to and should therefore not be represented in the DT. > > As a result we have proposed a scheme without explicit rotation. We specify what > coordinates X- and X+ should report at their ends (min, max) because the DT > programmer has to specify them anyways. Flipping is a result of defining these > coordinates in an ascending or descending way. Only swapping of the X and Y > wires can’t be implicitly defined so it has its own property. So the scheme we > have proposed tries to optimize the efforts needed to adapt new boards and write > DTs and focus the DT on hardware description. > > As a bonus we also specify the min and max value to be reported for the touch > pressure (Z axis) using the same basic principle. > > And it is a pure add-on on top of the existing driver so that it attempts not > to break existing device trees. from what I can see there are no in-tree-users using any of the new properties. > Maybe could you accept it as a first step for this specific driver (and let’s do > the big standardization work later on)? That does not work, since you create an ABI. -- Sebastian