Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753792AbZGLCF2 (ORCPT ); Sat, 11 Jul 2009 22:05:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751930AbZGLCFS (ORCPT ); Sat, 11 Jul 2009 22:05:18 -0400 Received: from mga02.intel.com ([134.134.136.20]:13829 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751879AbZGLCFR convert rfc822-to-8bit (ORCPT ); Sat, 11 Jul 2009 22:05:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.42,385,1243839600"; d="scan'208";a="532048245" From: "Mahalingam, Nithish" To: "Rafael J. Wysocki" CC: Magnus Damm , Alan Stern , Greg KH , LKML , ACPI Devel Maling List , Linux-pm mailing list , Ingo Molnar , Arjan van de Ven Date: Sun, 12 Jul 2009 07:35:07 +0530 Subject: RE: [linux-pm] [RFC][PATCH] PM: Introduce core framework for run-time PM of I/O devices (rev. 8) Thread-Topic: [linux-pm] [RFC][PATCH] PM: Introduce core framework for run-time PM of I/O devices (rev. 8) Thread-Index: AcoCF/SFOnfcuPOtSaGB+VA3eNH6TwAfFxHQ Message-ID: <175E0F9A9EFCEA46A65F5552BB057298BB5F43F0@bgsmsx502.gar.corp.intel.com> References: <175E0F9A9EFCEA46A65F5552BB057298BB5F3EA2@bgsmsx502.gar.corp.intel.com> <200907111308.44388.rjw@sisk.pl> In-Reply-To: <200907111308.44388.rjw@sisk.pl> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US 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: 1784 Lines: 40 >Hi, > >> I am newbee to this mailing list. Please excuse me if I am talking nonsense here. >> >> >> >> On Thu, Jul 9, 2009 at 10:48 PM, Alan Stern wrote: >>>> On Thu, 9 Jul 2009, Magnus Damm wrote: >>>> >>>> Clocks should be stopped as soon as possible without any delay. The >>>> clock stopping is very cheap performance wise. Also, the clock >>>> stopping is done on bus level without invoking any driver callbacks. >>>>> Delaying the clock stopping does not make any sense to me. >>>> >>>> In that case the device driver or bus subsystem should manage the >>>> device's clock directly. There's no need to tie it in with the runtime >>>> PM framework. Simply start the clock before each I/O operation and >>>> stop it afterward. >> >>> It's not that easy. The clock needs to be enabled to let the hardware >>> device perform device specific stuff. For instance, the clock for the >>> LCD controller needs to be on to redraw the screen. When the driver >>> knows that it's done with the clock it can notify the bus using >>> Runtime PM. >> >> Is there any plan to look into the "Clock Framework" that was developed as >> part of OMAP and extending this to make it generic for all platforms? >I don't have any plan to do that and I heaven't heard of anyone planning to do >it. Thanks for the reply Rafael. I felt if we are talking about controlling a device clock from a runtime PM framework we should look at extending the Clock framework rather than re-inventing things. Regards, Nithish Mahalingam -- 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/