From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 1/5] I2C: LM8323: Introduce lm8323 keypad driver Date: Mon, 14 Apr 2008 11:02:09 -0700 Message-ID: <20080414180209.GD26832@atomide.com> References: <1207742644-6260-1-git-send-email-felipe.balbi@nokia.com> <1207742644-6260-2-git-send-email-felipe.balbi@nokia.com> <20080409121124.GS7338@gandalf.research.nokia.com> <20080409180557.GA15913@kedavra.cpe.vivax.com.br> <20080409182804.GB24100@pure.research.nokia.com> <20080410001224.GD5897@intune.research.nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-02-bos.mailhop.org ([63.208.196.179]:56795 "EHLO mho-02-bos.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763340AbYDNSCP (ORCPT ); Mon, 14 Apr 2008 14:02:15 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: andrzej zaborowski Cc: Daniel Stone , Lauri Leukkunen , ext Felipe Balbi , felipe.balbi@nokia.com, linux-omap@vger.kernel.org, Eduardo Valentin * andrzej zaborowski [080409 18:12]: > On 10/04/2008, Daniel Stone wrote: > > On Thu, Apr 10, 2008 at 01:58:51AM +0200, ext andrzej zaborowski wrote: > > > On 09/04/2008, Lauri Leukkunen wrote: > > > > > > In my opinion kernel should provide "correct" data to user-space, not > > > > some pseudo-random interference from the LCD. > > > > > > I think this is discutible. There's a number of userspace libraries > > > written to talk tightly to the kernel and make that data more > > > "correct", one of them is tslib. Distros that come with tslib often > > > have a set of device-specific config files for tslib which load tslib > > > plugins for things like averaging, smoothing, checking bounds on the > > > values. > > > > > > One of the arguments for doing that in userspace is that of avoiding > > > every touchscreen driver redoing the same averaging and/or limit > > > checking code. I agree thought that it may be better to sacrifice > > > that for performance. > > > > > > If everyone's doing the same thing, move it to drivers/input/, not to > > userspace. Why should we be forced to have _two_ drivers and > > essentially maintain a stable kernel/userspace ABI between them? Surely > > it's better to only have _one_ hardware-specific driver, rather than > > half in the kernel, and half hidden behind an abstraction layer that is > > meant to let you just deal with input events without knowing stupid > > details about the hardware? > > For the ease of reconfiguration for one thing, tslib is quite > configurable with the plugins loaded by a config file. The ABI you > talk about is the same evdev ABI which is already stable. > > Averaging doesn't just cancel the noise from LCD, just lessens it but > there may be better things to do with it and the userspace already > knows how to deal with that. So it expects the kernel driver to be > more like a ADC driver. > > Of course doing it in drivers/input/ as configured by board files, > would also work if things were designed that way. Where to do the filtering should be discussed with the input people. Meanwhile, I'll push this patch to linux-omap tree. Tony