From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755380Ab3CAAiO (ORCPT ); Thu, 28 Feb 2013 19:38:14 -0500 Received: from mga03.intel.com ([143.182.124.21]:20654 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753764Ab3CAAiL convert rfc822-to-8bit (ORCPT ); Thu, 28 Feb 2013 19:38:11 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,758,1355126400"; d="scan'208";a="262889678" From: "Liu, Chuansheng" To: Alan Stern , "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" Subject: RE: [PATCH 4/5 V2] usb: call pm_runtime_put_sync in pm_runtime_get_sync failed case Thread-Topic: [PATCH 4/5 V2] usb: call pm_runtime_put_sync in pm_runtime_get_sync failed case Thread-Index: AQHOFZMb6/3FwJCIKUGVv/+y/WGnrJiO3A8AgAEh+oA= Date: Fri, 1 Mar 2013 00:38:07 +0000 Message-ID: <27240C0AC20F114CBF8149A2696CBE4A24253F@SHSMSX101.ccr.corp.intel.com> References: <1362042384.6212.25.camel@fli24-HP-Compaq-8100-Elite-CMT-PC> In-Reply-To: Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----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? Thanks. > > Alan Stern