Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752172AbcDEEUy (ORCPT ); Tue, 5 Apr 2016 00:20:54 -0400 Received: from mga01.intel.com ([192.55.52.88]:5217 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751292AbcDEEUw convert rfc822-to-8bit (ORCPT ); Tue, 5 Apr 2016 00:20:52 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,442,1455004800"; d="scan'208";a="680900472" From: "Brown, Len" To: "rcochran@linutronix.de" , "Gortmaker, Paul (Wind River)" CC: "linux-kernel@vger.kernel.org" , Len Brown , "linux-pm@vger.kernel.org" Subject: RE: [PATCH] drivers/idle: make intel_idle.c driver more explicitly non-modular Thread-Topic: [PATCH] drivers/idle: make intel_idle.c driver more explicitly non-modular Thread-Index: AQHRiE5P6QDRGO7mIUm9r+yb2qNnJp96vKOAgAB55QD//5N4UA== Date: Tue, 5 Apr 2016 04:20:47 +0000 Message-ID: <1A7043D5F58CCB44A599DFD55ED4C94846A1C854@fmsmsx115.amr.corp.intel.com> References: <1459099777-4962-1-git-send-email-paul.gortmaker@windriver.com> <20160404195535.GQ1778@windriver.com> <20160405031152.GA22836@linutronix.de> In-Reply-To: <20160405031152.GA22836@linutronix.de> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.1.200.106] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 808 Lines: 28 The first idle driver to register with cpuidle wins. intel_idle should always get the opportunity to probe and register before acpi_idle (processor_idle.c) When intel_idle was allowed to be modular, some distros build their kernel and loaded modules such that acpi_idle could probe first. In such a kernel, intel_idle became dead code. As intel_idle is a small driver, the q uick fix was to make it Y/N so that it would always probe before acpi_idle, no matter how acpi_idle is build and loaded. Yes, even though intel_idle is a tiny driver, I think it would be good to be able to unload it when it doesn't probe. Today, it appears that acpi_idle (acpi/processor_idle.c) is compiled Y/N. thanks, -Len ps. No, I do not believe that cpuidle should bother supporting changing idle drivers at run-time.