Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933395Ab0BEPTV (ORCPT ); Fri, 5 Feb 2010 10:19:21 -0500 Received: from netrider.rowland.org ([192.131.102.5]:39910 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932309Ab0BEPTT (ORCPT ); Fri, 5 Feb 2010 10:19:19 -0500 Date: Fri, 5 Feb 2010 10:19:18 -0500 (EST) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Pavel Machek cc: "Rafael J. Wysocki" , pm list , LKML , Jesse Barnes , Matthew Garrett , Greg KH Subject: Re: [PATCH 1/2] PM / Runtime: Add sysfs switch for disabling device run-time PM (rev. 2) In-Reply-To: <20100205062718.GA1384@ucw.cz> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1289 Lines: 32 On Fri, 5 Feb 2010, Pavel Machek wrote: > > > > > + * The default for all devices is "auto", which means that devices may be > > > > + * subject to automatic power management, depending on their drivers. > > > > > > Is it wise to specify 'auto' default value for devices without runtime > > > pm? > > > > Yes, it is. It means the user space doesn't care whether or not the device is > > power managed at run-time. > > Well, defaulting to 'on' for drivers when runtime pm is experimental > seems logical. and there will be such drivers... It's really not very important what the default setting is. Runtime PM is always initially disabled, regardless of the "auto"/"on" setting, until the driver explicitly enables it. At that time the driver also has the option of changing the setting from "auto" to "on". So if a driver writer wants to support runtime PM but thinks that his implementation (or the device!) may be buggy, he can easily arrange things so the user has to change the sysfs setting to make anything happen. Alan Stern -- 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/