Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752989AbZDTFyn (ORCPT ); Mon, 20 Apr 2009 01:54:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752712AbZDTFye (ORCPT ); Mon, 20 Apr 2009 01:54:34 -0400 Received: from relay.atmel.no ([80.232.32.139]:53521 "EHLO relay.atmel.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752574AbZDTFyd (ORCPT ); Mon, 20 Apr 2009 01:54:33 -0400 Date: Mon, 20 Apr 2009 07:54:01 +0200 From: Hans-Christian Egtvedt To: Ben Nizette Cc: "haavard.skinnemoen" , kernel , linux-kernel Subject: Re: [PATCH] favr32: improve touchscreen response Message-ID: <20090420075401.62d6d782@hcegtvedt> In-Reply-To: <1240195013.24329.38.camel@linux-51e8.site> References: <1240195013.24329.38.camel@linux-51e8.site> Organization: Atmel X-Mailer: Claws Mail 3.6.1 (GTK+ 2.16.1; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2148 Lines: 59 On Mon, 20 Apr 2009 12:36:53 +1000 Ben Nizette wrote: > The ezLCD+101 board (to which an favr-32 is fitted) has a long, > unshielded, nasty lead between the touch panel and the ads7843 touch > controller. In order to get satisfactory response then, we need to > employ every noise-reduction trick in the driver's arsenal. After > extensive fiddling I've found some good settings: > > 1) We keep vref on all the time to dramatically reduce settling times > (at the cost of a tiny increase in power consumption). > > 2) Despite 1 the settling time is still non-zero. 500uS is plenty of > time for the signals to settle > > 3) Despite 1 and 2 there's still a little bit of noise around. By > setting a pen recheck delay we make the panel feel less touchy and > twitchy. > > Someone with more time and patience myself might be able to tune this > numbers further but these settings are now perfectly acceptable for > normal use. > > Tested on ezLCD+101 though should only improve response on other > ezLCD+/ favr-32 boards too. > > Signed-off-by: Ben Nizette > Acked-by: Hans-Christian Egtvedt > --- > arch/avr32/boards/favr-32/setup.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/arch/avr32/boards/favr-32/setup.c > b/arch/avr32/boards/favr-32/setup.c index 58203d1..f1152fa 100644 > --- a/arch/avr32/boards/favr-32/setup.c > +++ b/arch/avr32/boards/favr-32/setup.c > @@ -72,6 +72,10 @@ static struct ads7846_platform_data ads7843_data = > { .debounce_max = 20, > .debounce_rep = 4, > .debounce_tol = 5, > + > + .keep_vref_on = true, > + .settle_delay_usecs = 500, > + .penirq_recheck_delay_usecs = 100, > > /* The ads7843 pendown irq is just connected to regular > * gpio and therefore can only trigger interrupts on -- Best regards, Hans-Christian Egtvedt -- 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/