From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753497AbbFHXQV (ORCPT ); Mon, 8 Jun 2015 19:16:21 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:65521 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753206AbbFHXQO (ORCPT ); Mon, 8 Jun 2015 19:16:14 -0400 From: "Rafael J. Wysocki" To: Andy Shevchenko Cc: linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, Greg Kroah-Hartman , Vinod Koul , Lee Jones , Andrew Morton , Mika Westerberg , linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Heikki Krogerus , Jarkko Nikula , "Wysocki, Rafael J" , Mike Turquette Subject: Re: [PATCH v3 3/8] Driver core: wakeup the parent device before trying probe Date: Tue, 09 Jun 2015 01:42 +0200 Message-ID: <6646339.jahMH2QKDR@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.1.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1433170082-117462-4-git-send-email-andriy.shevchenko@linux.intel.com> References: <1433170082-117462-1-git-send-email-andriy.shevchenko@linux.intel.com> <1433170082-117462-4-git-send-email-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday, June 01, 2015 05:47:57 PM Andy Shevchenko wrote: > From: Heikki Krogerus > > If the parent is still suspended when driver probe is > attempted, the result may be failure. > > For example, if the parent is a PCI MFD device that has been > suspended when we try to probe our device, any register > reads will return 0xffffffff. > > To fix the problem, making sure the parent is always awake > before attempting driver probe. > > Signed-off-by: Heikki Krogerus > Signed-off-by: Andy Shevchenko > --- > drivers/base/dd.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index e843fdb..cfbeff3 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -399,6 +399,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe); > * > * This function must be called with @dev lock held. When called for a > * USB interface, @dev->parent lock must be held as well. > + * > + * If device has a parent it will be powered on during device's probe(). > */ > int driver_probe_device(struct device_driver *drv, struct device *dev) > { > @@ -410,10 +412,16 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) > pr_debug("bus: '%s': %s: matched device %s with driver %s\n", > drv->bus->name, __func__, dev_name(dev), drv->name); > > + if (dev->parent) > + pm_runtime_get_sync(dev->parent); > + For some bus types that will resume and suspend the parent for many times in a row in device_attach() until an appropriate driver is found. Would it be more efficient to call it once before the bus_for_each_drv() loop in there? > pm_runtime_barrier(dev); > ret = really_probe(dev, drv); > pm_request_idle(dev); > > + if (dev->parent) > + pm_runtime_put_sync(dev->parent); Is there anything particularly wrong with calling pm_runtime_put() here instead? > + > return ret; > } > > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.