Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932421AbaFPRkJ (ORCPT ); Mon, 16 Jun 2014 13:40:09 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:54314 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932243AbaFPRkG (ORCPT ); Mon, 16 Jun 2014 13:40:06 -0400 Date: Mon, 16 Jun 2014 13:40:05 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Allen Yu cc: "Rafael J. Wysocki" , Pavel Machek , Len Brown , Greg Kroah-Hartman , , Subject: Re: [PATCH 1/1] PM / Runtime: let rpm_resume fail if rpm disabled and device suspended. In-Reply-To: <1402740209-16432-1-git-send-email-alleny@nvidia.com> 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 On Sat, 14 Jun 2014, Allen Yu wrote: > --- a/drivers/base/power/runtime.c > +++ b/drivers/base/power/runtime.c > @@ -608,7 +608,7 @@ static int rpm_resume(struct device *dev, int rpmflags) > repeat: > if (dev->power.runtime_error) > retval = -EINVAL; > - else if (dev->power.disable_depth == 1 && dev->power.is_suspended > + else if (dev->power.disable_depth == 1 && !dev->power.is_suspended > && dev->power.runtime_status == RPM_ACTIVE) > retval = 1; For reasons having nothing to do with Allen's suggested change, I wonder if we shouldn't replace this line with something like: - else if (dev->power.disable_depth == 1 && dev->power.is_suspended + else if (dev->power.disable > 0 && !dev->power.is_suspended && dev->power.runtime_status == RPM_ACTIVE) retval = 1; It seems that I've been bitten by this several times in the past. When a device is disabled for runtime PM, and more or less permanently stuck in the RPM_ACTIVE state, calls to pm_runtime_resume() or pm_runtime_get_sync() shouldn't fail. For example, suppose some devices of a certain type support runtime power management but others don't. We naturally want to call pm_runtime_disable() for the ones that don't. But we also want the same driver to work for all the devices, which means that pm_runtime_get_sync() should return success -- otherwise the driver will think that something has gone wrong. Rafael, what do you think? 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/