Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753100Ab3JJF0I (ORCPT ); Thu, 10 Oct 2013 01:26:08 -0400 Received: from mga02.intel.com ([134.134.136.20]:11526 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751318Ab3JJF0F (ORCPT ); Thu, 10 Oct 2013 01:26:05 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,1069,1371106800"; d="scan'208";a="408658506" From: Jani Nikula To: Aaron Lu , "Rafael J. Wysocki" Cc: linux-acpi@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Daniel Vetter , Matthew Garrett , Seth Forshee , Lee Chun-Yi , Richard Purdie , Igor Gnatenko , Yves-Alexis Perez , Felipe Contreras , Ben Jencks , Steven Newbury , James Hogan , Kamal Mostafa , Joerg Platte , Kalle Valo , Martin Steigerwald , =?utf-8?Q?J=C3=B6rg?= Otte , Mike Galbraith , platform-driver-x86@vger.kernel.org, Mika Westerberg , Henrique de Moraes Holschuh Subject: Re: [PATCH v4 1/4] backlight: introduce backlight_device_registered In-Reply-To: <525632AE.2080909@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <1381214401-24672-1-git-send-email-aaron.lu@intel.com> <1381214401-24672-2-git-send-email-aaron.lu@intel.com> <2202423.8QyNjoNEPr@vostro.rjw.lan> <5255FAC5.2090105@intel.com> <878uy1694u.fsf@intel.com> <525632AE.2080909@intel.com> User-Agent: Notmuch/0.16+88~gce1bf71 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-pc-linux-gnu) Date: Thu, 10 Oct 2013 08:23:02 +0300 Message-ID: <874n8p66o9.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1819 Lines: 59 On Thu, 10 Oct 2013, Aaron Lu wrote: > On 10/10/2013 12:29 PM, Jani Nikula wrote: >> On Thu, 10 Oct 2013, Aaron Lu wrote: >>> On 10/10/2013 08:25 AM, Rafael J. Wysocki wrote: >>>> On Tuesday, October 08, 2013 02:39:58 PM Aaron Lu wrote: >>>>> +bool backlight_device_registered(enum backlight_type type) >>>>> +{ >>>>> + bool found = false; >>>>> + struct backlight_device *bd; >>>>> + >>>>> + mutex_lock(&bd_list_mutex); >>>>> + list_for_each_entry(bd, &bd_list_head, entry) { >>>>> + if (bd->props.type == type) { >>>>> + found = true; >>>>> + break; >>>>> + } >>>>> + } >>>> >>>> Isn't it useful to be able to register more than one backlight device of the >>>> same type sometimes? >>> >>> I think so for some kind of computers. OTOH, the above function should >>> be enough for the problem we are solving here, if someday we need to >>> differentiate, we can enhance the code then. >> >> Since both Baytrail and Haswell already have two backlight PWMs, this >> may be needed sooner than you think. But we shouldn't let that block > > Do we need to differentiate which backlight PWM is registered to decide > if ACPI video backlight interface should be skipped? My understanding is > no. That's correct. If things change, we can fix it then. Jani. > > Thanks, > Aaron > >> fixing the more urgent issue we have now. So I'm fine with this. It >> doesn't prevent one from registering more than one device of the same >> type anyway. >> >> BR, >> Jani. >> >> >> > -- Jani Nikula, Intel Open Source Technology Center -- 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/