From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Neukum Subject: Re: [patch update] Re: Run-time PM idea (was: Re: [RFC][PATCH 0/2] PM: Rearrange core suspend code) Date: Thu, 11 Jun 2009 01:07:22 +0200 Message-ID: <200906110107.23023.oliver__39368.4615301483$1244675335$gmane$org@neukum.org> References: <200906102338.35183.oliver@neukum.org> <200906110001.20718.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <200906110001.20718.rjw@sisk.pl> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: "Rafael J. Wysocki" Cc: ACPI Devel Maling List , linux-pm@lists.linux-foundation.org, LKML List-Id: linux-pm@vger.kernel.org Am Donnerstag, 11. Juni 2009 00:01:20 schrieb Rafael J. Wysocki: > We have queued up resume requests for the device's parent, its parent etc= ., > the topmost one goes first. =A0The workqueue is singlethread, so > pm_autoresume() is going to be run for all parents before the device > itself, so if that were the only resume mechanism, it would be enough to > check if the parent is RPM_ACTIVE. A (IDLE) / \ B (SUSPENDED) C (SUSPENDED) Suppose C is to be resumed. This means first in case of A the request to suspend would be cancelled. Here you drop the locks: + && (dev->parent->power.runtime_status =3D=3D RPM_IDLE + || dev->parent->power.runtime_status =3D=3D RPM_SUSPENDING + || dev->parent->power.runtime_status =3D=3D RPM_SUSPENDED)) { + spin_unlock_irqrestore(&dev->power.lock, flags); + spin_unlock_irqrestore(&dev->parent->power.lock, parent_fla= gs); + + /* We have to resume the parent first. */ + pm_request_resume(dev->parent); But after pm_request_resume() returns there's no means to make sure nothing alters it back to RPM_SUSPENDED. The workqueue doesn't help you because you've scheduled nothing by that time. The suspension will work because C is still in RPM_SUSPENDED. Regards Oliver