From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Mack Subject: Re: [PATCH v2 0/3] Input: rotary-encoder - use more than two gpios Date: Tue, 2 Feb 2016 13:08:07 +0100 Message-ID: <56B09C27.8070009@zonque.org> References: <1454408678-6011-1-git-send-email-u.kleine-koenig@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from svenfoo.org ([82.94.215.22]:34927 "EHLO mail.zonque.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755177AbcBBMIK (ORCPT ); Tue, 2 Feb 2016 07:08:10 -0500 In-Reply-To: <1454408678-6011-1-git-send-email-u.kleine-koenig@pengutronix.de> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Ezequiel Garcia , Dmitry Torokhov , Sylvain Rochet , Johan Hovold , Haojian Zhuang , Robert Jarzmik Cc: devicetree@vger.kernel.org, kernel@pengutronix.de, linux-arm-kernel@lists.infradead.org, linux-input@vger.kernel.org Hi Uwe, Thanks for the update. On 02/02/2016 11:24 AM, Uwe Kleine-K=C3=B6nig wrote: > Some time ago I sent a v1 of this, now after testing the changes more > deeply patch 3 changed a bit. The old series started with >=20 > Date: Wed, 2 Dec 2015 11:07:11 +0100 = =20 > From: Uwe Kleine-K=C3=B6nig = =20 > Subject: [PATCH RFC 0/3] input: rotary_encoder: use more than two gp= ios as input =20 > Message-Id: <1449050834-31779-1-git-send-email-u.kleine-koenig@pengu= tronix.de> =20 >=20 > The two first patches are just preparation for the third patch. >=20 > There is an obvious improvement that allows detection of quick change= s > more reliably with >2 gpios, but I didn't implement this yet. (With 4 > GPIOs you can distinguish a counter clockwise movement of three state= s > from a clock wise movement of a single state. Still the patch is usef= ul > as it makes these devices work at all. >=20 > My test device looks as follows: >=20 > rotary@0 { > compatible =3D "rotary-encoder"; > gpios =3D <&gpio4 12 GPIO_ACTIVE_HIGH>, <&gpio4 11 GP= IO_ACTIVE_HIGH>, <&gpio4 10 GPIO_ACTIVE_HIGH>, <&gpio4 9 GPIO_ACTIVE_HI= GH>; >=20 > rotary-encoder,steps =3D <16>; > rotary-encoder,steps-per-period =3D <16>; > }; >=20 > While Daniel Mack and Rojhalat Ibrahim agreed that this device is an > absolute encoder and should be supported by a simpler logic, I still > consider it worthwhile to get these patches in as a first step. Also = the > binding looks right, so IMHO the comments shouldn't stop this series > from going in. I still don't understand why this is implemented that way, rather than going for a much simpler logic of interpretation that also allows users to read out the absolute position. The code to read the value would be really just as simple as reading al= l GPIOs and or-ing their values into the result, and skip the state machine completely. This code would be active if a new attribute (something like 'rotary-encoder,hardware-absolute') is set, or even implicitly, when more than 2 GPIOs are specified. Is there any reason for not doing that? Thanks, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-input" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html