Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752873Ab0AZJwa (ORCPT ); Tue, 26 Jan 2010 04:52:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752652Ab0AZJwY (ORCPT ); Tue, 26 Jan 2010 04:52:24 -0500 Received: from mail-pw0-f42.google.com ([209.85.160.42]:61020 "EHLO mail-pw0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752200Ab0AZJwX (ORCPT ); Tue, 26 Jan 2010 04:52:23 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=eKycl03CY1xCE67Gn42HMy84L3jOhySwUbhU2jdWi41fAKC6qSs7q/rwRXSONc1ic4 +rRDJ6BDCMqftlyxmlnkUULIKqvlQLVEAgpxRe57gEhkCuDJKyxq6L5Yx78vtmWqUHhH xrlStdOBNhx/Mpy9IXybk8QnYBrknsJ3yBVSw= Date: Tue, 26 Jan 2010 01:52:17 -0800 From: Dmitry Torokhov To: Alberto Panizzo Cc: H Hartley Sweeten , linux-input@vger.kernel.org, linux-kernel , linux-arm-kernel-infradead , Sascha linux-arm Subject: Re: [PATCH v2] input: MXC: add mxc-keypad driver to support the Keypad Port present in the mxc application processors family. Message-ID: <20100126095217.GC3480@core.coreip.homeip.net> References: <1262977099.2050.75.camel@climbing-alby> <1263664125.4350.18.camel@realization> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1263664125.4350.18.camel@realization> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2023 Lines: 50 Hi Alberto, On Sat, Jan 16, 2010 at 06:48:45PM +0100, Alberto Panizzo wrote: > Version 2 for this driver proposal. > -------------------------------------------------------------------------------- > The MXC family of Application Processors is shipped with a Keypad Port > supported now by this driver. > > The peripheral can control up to an 8x8 matrix key pad where all the scanning > procedure is done via software. > > The hardware provide two interrupts: one for a key pressed (KDI) and one for > all key releases (KRI). There is also a simple circuit for glitch reduction > (said for synchronization) made by two series of 3 D-latches clocked by the > keypad-clock that stabilize the interrupts sources. > KDI and KRI are fired only if the respective conditions are maintained for at > last 4 keypad-clock cycle. > > Those simple synchronization circuits are used also for multiple key pressures: > between a KDI and a KRI the driver reset the sync circuit and re-enable the KDI > interrupt so after 3 keypad-clock cycle another KDI is fired making possible to > repeat the matrix scan operation. > Nicely looking driver, thank you. > This algorithm is done via a threaded management of the keypad interrupt source > and delayed by a proper (and longer) debounce interval controlled by the > platform initialization. This I am not so sure about - the core of the matrix scan routine does not sleep so I wonder if starting a separate thread is not too wasteful in this case - you can easily do whan you want with a timer, no? > + > + /* > + * Search for rows and cols enabled > + */ > + keymap_data = (struct matrix_keymap_data *) pdata->keymap_data; Why do you need to cast away constness instead of declaring keymap_data as const pointer? -- Dmitry -- 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/