From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752779AbdBJQ13 (ORCPT ); Fri, 10 Feb 2017 11:27:29 -0500 Received: from mail.ltec.ch ([95.143.48.181]:54396 "EHLO mail.ltec.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751767AbdBJQ12 (ORCPT ); Fri, 10 Feb 2017 11:27:28 -0500 Subject: Re: [PATCH] leds: pca9532: Extend pca9532 device tree support To: Pavel Machek Cc: Jacek Anaszewski , riku.voipio@iki.fi, rpurdie@rpsys.net, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org References: <725c338e-af4c-1332-6c27-462c2dc1b97f@gmail.com> <3bfc9206-18c7-470b-ca53-d7bdb9a34f0a@ltec.ch> <20170209142408.GB23373@xo-6d-61-c0.localdomain> From: Felix Brack Message-ID: <1e470346-3394-c2aa-2fa4-508928c178d2@ltec.ch> Date: Fri, 10 Feb 2017 17:26:32 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20170209142408.GB23373@xo-6d-61-c0.localdomain> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Pavel, Hello Jacek On 09.02.2017 15:24, Pavel Machek wrote: > Hi! > >>>> This might be a misunderstanding. My patch is not meant to replace >>>> anything for driving the LEDs once the kernel is fully loaded. The LED >>>> subsystem offers quite a lot of possibilities to do this. >>>> >>>> My patch mainly deals with the 'default' state of the LEDs immediately >>>> when the driver gets loaded. >>>> Here is an example: I have a system with a LED named 'RUN' which is >>>> turned on steady by U-Boot (indicating "system booting"). When the >>>> PCA9532 driver loads this LED gets turned off due to initialization. >>>> However I would like it remain lit until later a script will make that >>>> 'RUN' LED blink (indicating "system running"). This script will of >>>> course use the existing LED subsystem to do so. To keep the 'RUN' LED >>>> lit I need the DT property 'default-state' being set to 'PCA9532_KEEP'. >>> >>> It looks like all you need is default-state property. >> >> For the example with keeping the 'RUN' led turned on, yes. However I >> would have to configure PSC and PWM registers to make the 'RUN' LED >> blink, for example. > > Is that really useful? Keeping the state from u-boot until userland can take > control... ok, why not. > > If it is useful, right, you can do it. But it will have to be generic for all > the LEDs, not like this. > > You'll want something like > > default_trigger = blinking; > default_trigger_parameters = < 2 sec on, 1 sec off >; > > or something. You may want to coordinate with the USB LED people, which want > default triggers with parametrs. > > Okay, I absolutely agree with you two. The driver should hide hardware specific details (such as chip registers) as much as possible. My approach does the opposite! I will submit a new version of the patch that should conform much better to existing DT bindings for LEDs. many thanks, Felix