Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752256AbaACPXn (ORCPT ); Fri, 3 Jan 2014 10:23:43 -0500 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:33510 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751529AbaACPXl (ORCPT ); Fri, 3 Jan 2014 10:23:41 -0500 Date: Fri, 3 Jan 2014 15:23:13 +0000 From: One Thousand Gnomes To: Bryan Wu Cc: David Lang , Joe Xue , "rpurdie@rpsys.net" , "rob@landley.net" , "milo.kim@ti.com" , "pavel@ucw.cz" , "linux-leds@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" Subject: Re: [PATCH] Add LED pattern trigger Message-ID: <20140103152313.4fd5c48f@alan.etchedpixels.co.uk> In-Reply-To: References: <1388362275-1618-1-git-send-email-lgxue@hotmail.com> <20131230162158.7420e811@alan.etchedpixels.co.uk> <20140101201053.12be7d27@alan.etchedpixels.co.uk> <20140101230135.48f6f781@alan.etchedpixels.co.uk> Organization: Intel Corporation X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.20; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1368 Lines: 31 > Also for user space application, I think we don't have any user space > LED library, if I'm wrong please correct me. Why there is no such > library, since we don't need it. No - rght now it is a case of "we don't have a kernel driver because we don't need one" > IMHO, firstly we should take this trigger into kernel, most time it > works as a module. But we need to define a good interface between > kernel and user space. You need the interface defined first. To do that it needs to reflect the actual hardware accelerated devices, and also to deal with resource management for those devices if necessary (eg if they can only manage one led of a set at a time). Your API can't handle things like brightness level, cross-fades (which require multiple LEDs handled as one unit) and the like. So the starting point has to be the hardware accelerated devices, whether you then support software emulation in kernel or user space is a follow on discussion. What the kernel/user API is also has to be a follow on discussion from understanding what the hardware accelerated devices can do and what their limits are. Alan -- 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/