Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760016Ab3GSIrN (ORCPT ); Fri, 19 Jul 2013 04:47:13 -0400 Received: from mail-la0-f47.google.com ([209.85.215.47]:52056 "EHLO mail-la0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752176Ab3GSIrH (ORCPT ); Fri, 19 Jul 2013 04:47:07 -0400 MIME-Version: 1.0 In-Reply-To: <20130718192416.GA526@polaris.bitmath.org> References: <1373620101-16113-1-git-send-email-benjamin.tissoires@redhat.com> <20130718192416.GA526@polaris.bitmath.org> Date: Fri, 19 Jul 2013 10:47:05 +0200 Message-ID: Subject: Re: [PATCH] HID: multitouch: do not init reports for multitouch devices From: Benjamin Tissoires To: Henrik Rydberg Cc: Benjamin Tissoires , Jiri Kosina , Stephane Chatty , linux-input , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1986 Lines: 42 Hi Henrik, On Thu, Jul 18, 2013 at 9:24 PM, wrote: > Hi Benjamin, > >> Some multitouch screens do not like to be polled for input reports. >> However, the Win8 spec says that all touches should be sent during >> each report, making the initialization of reports unnecessary. >> The Win7 spec is less precise, but we can safely assume that when >> the module is loaded (at boot), no one is touching the screen. >> >> Add the quirk HID_QUIRK_NO_INIT_REPORTS so that we do not have to >> introduce a quirk for each problematic device. > > I assume you have tested thoroughly for regressions? How about odd > eGalax devices, for instance? Changes affecting existing hardware > makes me nervous. Is it so bad to add this quirk on a per-device > basis? Or perhaps turned on by default for win8 devices only? Aargh, I forgot the eGalax... (I don't have it anymore on my desk). I was pretty confident because Win [7-8] is not doing any quirks for the multitouch devices, and I had in mind that it did not asked for the reports at startup (at least, I am sure about it for HID/I2C). I'm not sure win 8 devices is a sufficient denominator, because this init sequence is not mentioned anywhere in the Win 8 spec. It's true that we are going to see fewer Win 7 devices, but I would say it's the exact same problem for win 7 and 8. Moreover, asking this for Win 8 devices only will forces us to detect it in core before hid-multitouch is loaded because the init reports is called before the parsing. If I capture the Win 7 & Win 8 initialization events and I observe that they do not retrieve the reports, will it be sufficient as a guarantee to include this patch even if it is not widely tested under Linux? Cheers, Benjamin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/