Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755556AbZGIV5F (ORCPT ); Thu, 9 Jul 2009 17:57:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754696AbZGIV4y (ORCPT ); Thu, 9 Jul 2009 17:56:54 -0400 Received: from mga03.intel.com ([143.182.124.21]:27908 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753715AbZGIV4x convert rfc822-to-8bit (ORCPT ); Thu, 9 Jul 2009 17:56:53 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.42,375,1243839600"; d="scan'208";a="163376589" From: "Mahalingam, Nithish" To: Magnus Damm , Alan Stern CC: Greg KH , LKML , ACPI Devel Maling List , Linux-pm mailing list , Ingo Molnar , Arjan van de Ven Date: Fri, 10 Jul 2009 03:26:45 +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: AcoAqy8XnjCmJfmaTgicBn6D7E6MngANCe3g Message-ID: <175E0F9A9EFCEA46A65F5552BB057298BB5F3EA2@bgsmsx502.gar.corp.intel.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="iso-8859-1" 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: 1413 Lines: 31 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? -- 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/