Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753014Ab3H1NOB (ORCPT ); Wed, 28 Aug 2013 09:14:01 -0400 Received: from mail-ob0-f179.google.com ([209.85.214.179]:61137 "EHLO mail-ob0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752641Ab3H1NN6 (ORCPT ); Wed, 28 Aug 2013 09:13:58 -0400 MIME-Version: 1.0 In-Reply-To: <521C587E.6050706@atmel.com> References: <1377379926-11163-1-git-send-email-b.brezillon@overkiz.com> <1377380109-11247-1-git-send-email-b.brezillon@overkiz.com> <521B875E.1010605@wwwdotorg.org> <521B89D1.6010902@overkiz.com> <521C2347.4080702@wwwdotorg.org> <521C4451.1060908@overkiz.com> <521C587E.6050706@atmel.com> Date: Wed, 28 Aug 2013 15:13:58 +0200 Message-ID: Subject: Re: [RFC PATCH 1/3] pinctrl: add new generic pinconf config for deglitch filter From: Linus Walleij To: Nicolas Ferre Cc: boris brezillon , Stephen Warren , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Rob Landley , Russell King , Jean-Christophe Plagniol-Villard , Jiri Kosina , Masanari Iida , Richard Genoud , Heiko Stuebner , James Hogan , "devicetree@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2261 Lines: 58 On Tue, Aug 27, 2013 at 9:42 AM, Nicolas Ferre wrote: > On 27/08/2013 08:16, boris brezillon : > Deglitch and > Debounce filters are different features in at91 (even if they pursuit the > same goal). So I do prefer to let the user choose which feature is preferred > for his application and add a different flag. Electrically speaking debounce and deglitch are totally different things. Debounce is for, well debouncing. To even out the effect of pressing a button which due to mechanical characteristics create a sharp series of spikes like that: _ _ _| |_| |_ I highly suspect that "deglitch" is either: - A one-spike version of the above (in which case a custom config may be warranted) or - What we usually call schmitt-trigger, i.e. handling of analog swing-in. Can you describe exactly what the two features do, in electrical terms? > The question is: how much this "generic" pinconf is... well... generic! And > it is not a answer I can give. The generic configs are defined from electrical use-cases that appear in practice and also have the character of appearing in similar implementations in I/O cells of several vendors, to the point that from a software perspective they are identical. > On the other hand, if the "generic" is not going to overcome the native > pinctrl, I do not feel like switching to this at the cost of changing the > whole dtsi/dts entries that we already have. The question we ask in this case is whether the electrical construction is so fantastically unique and ingenious that no other ASIC pad implementer sitting in his chamber working on I/O cells would possibly ever come up with the same concept. If that is true, then it warrants its own, custom binding. If you ask some other randong cell implementer whether this is something they would do, and they say "yeah I have that in the next version of my cell library" then it is generic, because we will see the same thing in other systems as time moves on. Yours, Linus Walleij -- 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/