From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: Synchronized led trigger Date: Fri, 14 Aug 2015 10:40:53 +0200 Message-ID: <55CDA995.6010709@samsung.com> References: <715D9F6A60DF2F458F39683D45F6609A7E22E57B@VMPREVAS1.prevas.se> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:9461 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753500AbbHNIk6 (ORCPT ); Fri, 14 Aug 2015 04:40:58 -0400 Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout2.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NT200IGXDG6YI50@mailout2.w1.samsung.com> for linux-leds@vger.kernel.org; Fri, 14 Aug 2015 09:40:54 +0100 (BST) In-reply-to: <715D9F6A60DF2F458F39683D45F6609A7E22E57B@VMPREVAS1.prevas.se> Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: =?ISO-8859-1?Q?Sean_Nyekj=E6r?= Cc: "linux-leds@vger.kernel.org" Hi Sean, On 08/13/2015 09:37 AM, Sean Nyekj=E6r wrote: > Hi > > I couldn't find any synchronized led triggers in the kernel. The time= r trigger was blinking in random when I tried to set our 5 leds. :-) It is impossible to synchronize brightness setting operation for different devices. It would only make sense for two separate LED class devices exposed by a driver controlling one hardware device. Effectively the issue boils down to the problem of adding an API for synchronizing brightness setting operation for several LED class devices exposed by a single LED class driver. We were trying to implement similar functionality for synchronizing flash strobe for LED flash class devices, but it has been given up. You could try to pursue the subject if you want, here are references: [1], [2]. > So i created this led trigger, which can blink with a half and one hz= =2E > > Is there any place for something like this upstream? I'm prepared to = make changes so it can be configured by the dtb or some other way. > > Cheers > Sean Nyekj=E6r > [1] https://lwn.net/Articles/634465/ [2] http://www.spinics.net/lists/linux-leds/msg02995.html --=20 Best Regards, Jacek Anaszewski