From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754928Ab3CAAnr (ORCPT ); Thu, 28 Feb 2013 19:43:47 -0500 Received: from hydra.sisk.pl ([212.160.235.94]:48200 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751332Ab3CAAnn (ORCPT ); Thu, 28 Feb 2013 19:43:43 -0500 From: "Rafael J. Wysocki" To: "Liu, Chuansheng" Cc: Alan Stern , "Li, Fei" , "gregkh@linuxfoundation.org" , "Lan, Tianyu" , "sarah.a.sharp@linux.intel.com" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 4/5 V2] usb: call pm_runtime_put_sync in pm_runtime_get_sync failed case Date: Fri, 01 Mar 2013 01:50:30 +0100 Message-ID: <35852055.MkFUspWUco@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.8.0; KDE/4.9.5; x86_64; ; ) In-Reply-To: <27240C0AC20F114CBF8149A2696CBE4A24253F@SHSMSX101.ccr.corp.intel.com> References: <1362042384.6212.25.camel@fli24-HP-Compaq-8100-Elite-CMT-PC> <27240C0AC20F114CBF8149A2696CBE4A24253F@SHSMSX101.ccr.corp.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 Friday, March 01, 2013 12:38:07 AM Liu, Chuansheng wrote: > > > -----Original Message----- > > From: Alan Stern [mailto:stern@rowland.harvard.edu] > > Sent: Thursday, February 28, 2013 11:17 PM > > To: Li, Fei > > Cc: gregkh@linuxfoundation.org; Lan, Tianyu; sarah.a.sharp@linux.intel.com; > > rjw@sisk.pl; linux-usb@vger.kernel.org; linux-kernel@vger.kernel.org; Liu, > > Chuansheng > > Subject: Re: [PATCH 4/5 V2] usb: call pm_runtime_put_sync in > > pm_runtime_get_sync failed case > > > > On Thu, 28 Feb 2013, Li Fei wrote: > > > > > > > > Even in failed case of pm_runtime_get_sync, the usage_count > > > is incremented. In order to keep the usage_count with correct > > > value and runtime power management to behave correctly, call > > > pm_runtime_put(_sync) in such case. > > > > > > Signed-off-by Liu Chuansheng > > > Signed-off-by: Li Fei > > > --- > > > drivers/usb/core/hub.c | 3 ++- > > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > > > index 5480352..f72dede 100644 > > > --- a/drivers/usb/core/hub.c > > > +++ b/drivers/usb/core/hub.c > > > @@ -3148,12 +3148,13 @@ int usb_port_resume(struct usb_device *udev, > > pm_message_t msg) > > > > > > if (port_dev->did_runtime_put) { > > > status = pm_runtime_get_sync(&port_dev->dev); > > > - port_dev->did_runtime_put = false; > > > if (status < 0) { > > > dev_dbg(&udev->dev, "can't resume usb port, status %d\n", > > > status); > > > + pm_runtime_put_sync(&port_dev->dev); > > > return status; > > > } > > > + port_dev->did_runtime_put = false; > > > } > > > > I don't see much point in this. After a failed resume, the port's > > runtime PM status is undefined. Whether or not you do a > > pm_runtime_put_sync won't make any difference. > In case of failed resume, calling pm_runtime_put_sync() is just for decrease the dev->power.usage_count, > because pm_runtime_get_sync() always increase the dev->power.usage_count even failed. > > If not pairing runtime_get/put, after that case, the device can not enter runtime suspend any more due to dev->power.usage_count > 0 always. > Is it making sense? Well, not really. Before returning an error code, rpm_callback() assigns that code to dev->power.runtime_error and that will effectively disable runtime PM for dev going forward anyway. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.