From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Green Subject: Re: [PATCH] input/touchscreen: add S3C24XX SoC touchscreen input driver Date: Tue, 20 Oct 2009 11:09:07 +0100 Message-ID: <4ADD8C43.5060205@warmcat.com> References: <4ADC4D4D.5020508@gmail.com> <20091019120744.GB7412@n2100.arm.linux.org.uk> <2accc2ff0910192121t27387b90t9cfd5a5252aa00cc@mail.gmail.com> <20091020073946.GB723@n2100.arm.linux.org.uk> <2accc2ff0910200121g4f2c0839l96c7d99e4f4de47a@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2accc2ff0910200121g4f2c0839l96c7d99e4f4de47a@mail.gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: arhuaco@freaks-unidos.net Cc: Russell King - ARM Linux , dtor@mail.ru, Shine Liu , dmitry.torokhov@gmail.com, Maurus Cuelenaere , linux-input@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-input@vger.kernel.org On 10/20/09 09:21, Somebody in the thread at some point said: > We have problems when we don't have much pressure and in this case > there is a lot of noise and the events that are reported by the driver > are actually noise. This noise would be more common at pen-down before > the adc readings settle and at pen-up. Hi Nelson - Just a FYI, on the board I have been working on there is a capacitive sensor, AD7174. I wrote a driver for it which again uses the in-kernel median filter (the original Openmoko version I wrote chopped out at the moment) heavily and with really excellent results. The median filters are pretty much like magic for certain common kinds of noise. However, I just drop the median filter code into my tree in drivers/input/misc at the moment. What would be really a good result I think is if the filters turned up in ./lib in an easily reusable way. I think maybe it's a mistake to focus on the in-kernel filters being good for a particular touchscreen technology or even specifically touchscreens. I am sure other drivers doing something completely different with noisy instantaneously sampled data, that won't fit into tslib worldview at all, can also benefit from being able to clean up data in a standardized way before passing it down as an input event or back to the device or whatever. And once that's possible, touchscreen drivers of any sort have the standardized option to use it too if they have a reason. Just a thought, good luck :-) -Andy