From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?=C9ric_Piel?= Subject: Re: [PATCH] Input: elantech - correct x, y value range for v2 hardware Date: Wed, 17 Aug 2011 11:53:55 +0200 Message-ID: <4E4B8FB3.9090100@tudelft.nl> References: <1313380295-26226-1-git-send-email-jj_ding@emc.com.tw> <87hb5hligi.fsf@emc.com.tw> <4E4AE637.1090000@tudelft.nl> <87aab86d3v.fsf@emc.com.tw> <20110817064336.GA29361@core.coreip.homeip.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailservice.tudelft.nl ([130.161.131.5]:35506 "EHLO mailservice.tudelft.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751620Ab1HQJx7 (ORCPT ); Wed, 17 Aug 2011 05:53:59 -0400 In-Reply-To: <20110817064336.GA29361@core.coreip.homeip.net> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Dmitry Torokhov Cc: JJ Ding , linux-input@vger.kernel.org, Tom Lin , Aaron Huang , Daniel Kurtz Op 17-08-11 08:43, Dmitry Torokhov schreef: > Hi JJ, > >> As far as I know, this doesn't fix a bug. I just want to make sure t= he >> driver and what the firmware sends are consistent. > > As =C9ric mentioned, simply extending range to 12 bits is dangerous > because we might cause overflows. Blindly increasing ETP_YMAX_V2 is n= ot > a good idea either as userspace would expect much larger device and > reports would only cover fraction of its surface. We need to separate > ETP_YMAX_V2 as absolute maximum from reported coordinates range, like= it > is done in synaptics driver. Hi Dmitry, Concerning this point, I was wondering if it'd be ok to only send=20 negative values? Such as min/max are between -768 and 0. So that, if th= e=20 hardware actually has a bigger resolution, it can go down to -4095=20 without any overflow? It sounds the simplest way to report the=20 coordinate for a device which has an opposite axis. Or is it safer to=20 stay in the positive numbers, with min/max between 3328 and 4095, and i= n=20 case of bigger resolution the values go down to 0? Cheers, =C9ric -- 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