From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Silverstone Subject: Re: usbtouchscreen: Add support for Zytronic capacitive touchscreen Date: Tue, 13 Jan 2009 09:29:18 +0000 Message-ID: <1231838958.30531.3.camel@petitemort> References: <20090109121026.052643915@fluff.org.uk> <20090111234903.ZZRA012@mailhub.coreip.homeip.net> <1231751234.23618.6.camel@petitemort> <20090112212907.ZZRA012@mailhub.coreip.homeip.net> Reply-To: dsilvers@simtec.co.uk Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from batfish.pepperfish.net ([87.237.62.180]:46572 "EHLO flounder.pepperfish.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755533AbZAMJ3X (ORCPT ); Tue, 13 Jan 2009 04:29:23 -0500 In-Reply-To: <20090112212907.ZZRA012@mailhub.coreip.homeip.net> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Dmitry Torokhov Cc: Ben Dooks , linux-input@vger.kernel.org, vince@simtec.co.uk On Mon, 2009-01-12 at 21:33 -0800, Dmitry Torokhov wrote: > > > > + /* Always service the USB devices irq not just when the input device is > > > > + * open. > > > > + */ > > > > + int irq_always; > > > Why is this needed? > > Some devices (E.g. specifically this one) expect their interrupt > > endpoints to always be serviced. In this case, the device has an > > on-board watchdog and will reboot (disconnect and reconnecting to the > > USB) if it is not serviced in a timely fashion. > So what happens if driver was unloaded or there was no driver loaded at > all? Is this device constantly connecting and reconnecting? As I understand it; yes. (Some bits of hardware really are hideous things) Indeed if the driver fails to load quickly enough, the device might disconnect/reconnect before the driver can get hold of it. > > > > + dev->touch = 1; > > > > + dev->press = 1; > > > Since the device does not report real pressure readings don't try to > > > fake it, reporting touch is enough. > > I believe that this is because some userland libraries, particularly > > tslib, require the pressure reading in order to believe the device is > > functioning usefully. Specifically, consider plugins/input-raw of > > tslib's source package which uses pressure rather than touch. > Yes, I am aware of TSLIB case and I am telling everyone who submits > touchscreen drivers that they need to fix it. The policy is that > kernel should not generate fake events but present as accurate state > of hardware as possible. Unfortunately it's often harder to get people to change their userland than their kernel. It seems a pity to make the driver less useful during any longer-term effort to fix TSLIB. If acceptance of this patch is predicated on removing that then I guess we'll have to discuss it amongst ourselves and try and work out what we'd rather do. Is removing the fake pressure report a requirement or a would-like? Regards, Daniel. -- Daniel Silverstone http://www.simtec.co.uk/ PGP mail accepted and encouraged. Key Id: 2BC8 4016 2068 7895