From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fabio Baltieri Subject: Re: [PATCH] ACPI / PM: Take unusual configurations of power resources into account (was: Re: [GIT PATCH] USB patches for 3.9-rc1) Date: Sat, 23 Feb 2013 15:48:59 +0100 Message-ID: <20130223144859.GA2955@balto.lan> References: <20130222085954.GA4352@redhat.com> <1522889.3cbJt7lHsB@vostro.rjw.lan> <20130223114914.GA1786@balto.lan> <4258343.ok1n3SAim3@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-wg0-f54.google.com ([74.125.82.54]:62497 "EHLO mail-wg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758169Ab3BWOtS (ORCPT ); Sat, 23 Feb 2013 09:49:18 -0500 Received: by mail-wg0-f54.google.com with SMTP id fm10so1313162wgb.9 for ; Sat, 23 Feb 2013 06:49:17 -0800 (PST) Content-Disposition: inline In-Reply-To: <4258343.ok1n3SAim3@vostro.rjw.lan> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: Dave Jones , Greg KH , Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, tianyu.lan@intel.com, linux-acpi@vger.kernel.org, Bjorn Helgaas , linux-pci@vger.kernel.org > From: Rafael J. Wysocki > Subject: ACPI / PM: Take unusual configurations of power resources into account > > Commit d2e5f0c (ACPI / PCI: Rework the setup and cleanup of device > wakeup) moved the initial disabling of system wakeup for PCI devices > into a place where it can actually work and that exposed a hidden old > issue with crap^Wunusual system designs where the same power > resources are used for both wakeup power and device power control at > run time. > > Namely, say there is one power resource such that the ACPI power > state D0 of a PCI device depends on that power resource (i.e. the > device is in D0 when that power resource is "on") and it is used > as a wakeup power resource for the same device. Then, calling > acpi_pci_sleep_wake(pci_dev, false) for the device in question will > cause the reference counter of that power resource to drop to 0, > which in turn will cause it to be turned off. As a result, the > device will go into D3cold at that point, although it should have > stayed in D0. > > As it turns out, that happens to USB controllers on some laptops > and USB becomes unusable on those machines as a result, which is > a major regression from v3.8. > > To fix this problem, (1) increment the reference counters of wakup > power resources during their initialization if they are "on" > initially, (2) prevent acpi_disable_wakeup_device_power() from > decrementing the reference counters of wakeup power resources that > were not enabled for wakeup power previously, and (3) prevent > acpi_enable_wakeup_device_power() from incrementing the reference > counters of wakeup power resources that already are enabled for > wakeup power. > > In addition to that, if it is impossible to determine the initial > states of wakeup power resources, avoid enabling wakeup for devices > whose wakeup power depends on those power resources. > > Reported-by: Dave Jones > Reported-by: Fabio Baltieri > Signed-off-by: Rafael J. Wysocki Works just fine! Tested-by: Fabio Baltieri Thanks, Fabio -- Fabio Baltieri