Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751666AbdIRUvE (ORCPT ); Mon, 18 Sep 2017 16:51:04 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35975 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750714AbdIRUvB (ORCPT ); Mon, 18 Sep 2017 16:51:01 -0400 X-Google-Smtp-Source: AOwi7QBjKGC8bNTmf4lIhHf3vl7jAg72PSX5WntM4IkrtEGtl6T1bzKDd9T/CwSCUKakLFsAfCt80Q== Subject: Re: Vibrations in input vs. LED was Re: [PATCH v2 0/3] led: ledtrig-transient: add support for hrtimer To: Pavel Machek References: <20170913175400.42744-1-dtwlin@google.com> <20170913202032.GA30844@amd> <9c75c3a9-4123-c7f3-7725-45ba752d672a@gmail.com> <20170914205804.GA24339@amd> <7a611993-ebaa-08bb-b10c-ebe4fb9ca33a@gmail.com> <0076adca-f843-f99f-09ce-b9839b3e7706@gmail.com> <20170917182251.GA15328@amd> Cc: Dmitry Torokhov , "linux-input@vger.kernel.org" , David Lin , Jonathan Corbet , Richard Purdie , Hans de Goede , Greg Kroah-Hartman , Rob Herring , Rom Lemarchand , "linux-doc@vger.kernel.org" , lkml , "linux-leds@vger.kernel.org" From: Jacek Anaszewski X-Enigmail-Draft-Status: N1010 Message-ID: <9d5d045e-5019-e132-9449-7fb40b1b7895@gmail.com> Date: Mon, 18 Sep 2017 22:50:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170917182251.GA15328@amd> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2682 Lines: 64 Hi, On 09/17/2017 08:22 PM, Pavel Machek wrote: > Hi! > >>> If your objection is that FF is not easily engaged from the shell - >>> yes, but I do not think that actual users who want to do vibration do >>> that via shell either. On the other hand, can you drop privileges and >>> still allow a certain process control your vibrator via LED interface? >>> With FF you can pass an FD to whoever you deem worthy and later revoke >>> access. >>> >>> IOW sysfs interfaces are nice for quick hacks, but when you want to >>> use them in real frameworks, where you need to think about proper >>> namespaces, isolation, etc, etc, other kinds of interfaces might suit >>> better. >> >> I'd leave the decision to the user. We could add a note to the >> Documentation/leds/ledtrig-transient.txt that force feedback interface >> should be preferable choice for driving vibrate devices. > > We don't want to leave decision to the user; because then we'll end up > with userland applications having to support _both_ interfaces. This state has lasted for five years now. I don't recall any complaints. Do you? > Plus, it is not really your decision. Dmitry is maintainer of input > subsystem, input was doing force feedback for 10+ years, and he > already made a decision. It seems that you applied a fait accompli method here. Actually could you share what the decision is? AFAIK we're not discussing here any patch for the input subsystem? >> However only if following conditions are met: >> - force feedback driver supports gpio driven devices >> - there is sample application in tools/input showing how to >> setup gpio driven vibrate device with use of ff interface >> - it will be possible to setup vibrate interval with 1ms accuracy, >> similarly to what the discussed patch allows to do > > I agree these would be nice. Interested parties are welcome to help > there. But I don't think this should have any impact on LED > susbystem. Force feedback just does not belong to LED subsystem. You cut off important piece of my text from the beginning of this paragraph. It was: > I'd leave the decision to the user. We could add a note to the > Documentation/leds/ledtrig-transient.txt that force feedback interface > should be preferable choice for driving vibrate devices. > However only if following conditions are met: What I meant is that it is my decision, as a LED subsystem maintainer, to accept the addition of a note about some other subsystem offering an equivalent or even better substitute of the feature being available in the subsystem I am responsible for. And I will accept such a patch only if mentioned conditions are met. -- Best regards, Jacek Anaszewski