Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757564AbZFIHa5 (ORCPT ); Tue, 9 Jun 2009 03:30:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756820AbZFIHau (ORCPT ); Tue, 9 Jun 2009 03:30:50 -0400 Received: from smtp-out003.kontent.com ([81.88.40.217]:43494 "EHLO smtp-out003.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753897AbZFIHat convert rfc822-to-8bit (ORCPT ); Tue, 9 Jun 2009 03:30:49 -0400 From: Oliver Neukum To: "Rafael J. Wysocki" Subject: Re: [linux-pm] Run-time PM idea (was: Re: [RFC][PATCH 0/2] PM: Rearrange core suspend code) Date: Tue, 9 Jun 2009 09:31:37 +0200 User-Agent: KMail/1.10.3 (Linux/2.6.27.21-0.1-default; KDE/4.1.3; x86_64; ; ) Cc: Alan Stern , linux-pm@lists.linux-foundation.org, ACPI Devel Maling List , LKML References: <200906082331.58933.rjw@sisk.pl> In-Reply-To: <200906082331.58933.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200906090931.37626.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1489 Lines: 37 Am Montag, 8. Juni 2009 23:31:58 schrieb Rafael J. Wysocki: > If ->autosuspend() fails, the device power state may be known, but the core > can't be sure if the device is active. ?This information is available to > the driver and/or the bus type, which should change the status to whatever > is appropriate. That is quite confusing. You'd better define error returns. One that would mean that the suspension has failed but the device is unaffected, and another one that means that the device is in an undefined state now. > > The scheme doesn't include any mechanism for communicating runtime > > power information up the device tree. ?When a device is autosuspended, > > its parent's driver should be told so that the driver can consider > > autosuspending the parent. > > I thought the bus type's ->autosuspend() callback could take care of this. That can't work because you have to operate between busses. > > Likewise, if we want to autoresume a device below an autosuspended > > parent, the parent should be autoresumed first. ?Did you want to make the > > bus subsystem responsible for all of this? > > Yes, that was the idea. That is an important point. Can some subsytems operate with a parent still suspended? Regards Oliver -- 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/