From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757615Ab2DISQM (ORCPT ); Mon, 9 Apr 2012 14:16:12 -0400 Received: from g4t0014.houston.hp.com ([15.201.24.17]:30540 "EHLO g4t0014.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757367Ab2DISQL (ORCPT ); Mon, 9 Apr 2012 14:16:11 -0400 Message-ID: <1333995365.2871.17.camel@lorien2> Subject: Re: [PATCH RESEND] LEDS-One-Shot-Timer-Trigger-implementation From: Shuah Khan Reply-To: shuahkhan@gmail.com To: Dmitry Torokhov Cc: shuahkhan@gmail.com, Andrew Morton , neilb@suse.de, rpurdie@linux.intel.com, LKML Date: Mon, 09 Apr 2012 12:16:05 -0600 In-Reply-To: <20120409173703.GA18542@core.coreip.homeip.net> References: <1333310039.2879.4.camel@lorien2> <20120406165353.ab667eb0.akpm@linux-foundation.org> <1333808024.2728.39.camel@lorien2> <20120407215641.GA4539@core.coreip.homeip.net> <1333990549.2871.10.camel@lorien2> <20120409173703.GA18542@core.coreip.homeip.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.2- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-04-09 at 10:37 -0700, Dmitry Torokhov wrote: > On Mon, Apr 09, 2012 at 10:55:49AM -0600, Shuah Khan wrote: > > On Sat, 2012-04-07 at 14:56 -0700, Dmitry Torokhov wrote: > > > Hi Shuah, > > > > > > On Sat, Apr 07, 2012 at 08:13:44AM -0600, Shuah Khan wrote: > > > > > > > > > > +This feature will help implement vibrate functionality which requires one > > > > > > +time activation of vibrate mode without a continuous vibrate on/off cycles. > > > > > > > > > > They make vibrating LED? ;) > > > > > > > > > > What's going on here? You're proposing to repurpose the LEDs code to > > > > > drive vibration devices? Or some devices couple a LED with a vibration > > > > > device? > > > > > > > > I owe you filling in the blanks type explanation. Let me describe the > > > > use-case I am trying to address first. Vibrater function on phones is > > > > implemented using PWM pins on SoC or PMIC. When there is no such > > > > hardware present, a software solution is needed. Currently two drivers > > > > timed-gpio and timed-output (under staging/android in Linux 3.3) > > > > together implement the software vibrate feature. The main functionality > > > > it implements is the one time enables of timer to prevent user space > > > > crashes leaving the phone in vibrate mode causing the battery to drain. > > > > leds as it is implemented currently, is not suitable to address this > > > > use-case as it doesn't support one time enables. > > > > > > So why do not you use memoryless force feedback framework that other > > > devices use (see drivers/input/misc/*vibra.c drivers). > > > > > > > Dimitry, > > > > I took a look at these vibra* drivers. The three vibrate drivers are > > chip-set specific. The use-case I have is a non-chip set approach to > > address the use-case when vibrate hardware is not present. Are you > > envisioning a generic approach using ff-memoryless infrastructure? > > Shuah, > > I guess I am confused now. You need some form of hardware to make your > device to vibrate. > > What exactly are you trying to do? Are you trying to: > > 1. activate vibration on devices that can actually do it using LED > interface, or > > 2. use LEDs as an alternative to vibrate on devices that can't > physically vibrate? > > Thanks. What I meant by generic approach is a higher level interface that is not tied too closely to the underlying hardware. Similar to the leds-pwm.c and leds-gpio.c handle gpio and pwm based leds. The vibrate hardware in my sue-case is a gpio based and could pwm based on some phones. -- Shuah