From: "Liu, Chuansheng" <chuansheng.liu@intel.com>
To: Alan Stern <stern@rowland.harvard.edu>, "Li, Fei" <fei.li@intel.com>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"Lan, Tianyu" <tianyu.lan@intel.com>,
"sarah.a.sharp@linux.intel.com" <sarah.a.sharp@linux.intel.com>,
"rjw@sisk.pl" <rjw@sisk.pl>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@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, 1 Mar 2013 00:38:07 +0000 [thread overview]
Message-ID: <27240C0AC20F114CBF8149A2696CBE4A24253F@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1302281015330.1352-100000@iolanthe.rowland.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 <chuansheng.liu@intel.com>
> > Signed-off-by: Li Fei <fei.li@intel.com>
> > ---
> > 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
next prev parent reply other threads:[~2013-03-01 0:38 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-28 7:37 [PATCH 1/5] regmap: irq: call pm_runtime_put in pm_runtime_get_sync failed case Li Fei
2013-02-28 7:44 ` [PATCH 2/5] mmc: core: call pm_runtime_put_sync " Li Fei
2013-02-28 7:51 ` [PATCH 3/5] wl1251: " Li Fei
2013-02-28 7:57 ` [PATCH 4/5] usb: " Li Fei
2013-02-28 8:02 ` [PATCH 5/5] hwspinlock/core: call pm_runtime_put " Li Fei
2013-04-05 6:27 ` Ohad Ben-Cohen
2013-04-05 11:39 ` Rafael J. Wysocki
2013-04-05 11:42 ` Rafael J. Wysocki
2013-04-05 13:13 ` Li, Fei
2013-04-05 13:20 ` [PATCH 5/5 V2] " Li Fei
2013-04-05 14:46 ` Ohad Ben-Cohen
2013-02-28 8:37 ` [PATCH 4/5] usb: call pm_runtime_put_sync " Lan Tianyu
2013-02-28 9:00 ` Li, Fei
2013-02-28 15:14 ` Alan Stern
2013-02-28 9:06 ` [PATCH 4/5 V2] " Li Fei
2013-02-28 15:17 ` Alan Stern
2013-03-01 0:38 ` Liu, Chuansheng [this message]
2013-03-01 0:50 ` Rafael J. Wysocki
2013-03-01 0:59 ` Liu, Chuansheng
2013-03-01 2:18 ` Rafael J. Wysocki
2013-03-01 2:07 ` Liu, Chuansheng
2013-03-01 2:22 ` Rafael J. Wysocki
2013-03-01 2:23 ` Liu, Chuansheng
2013-03-01 2:57 ` [PATCH 4/5 V3] usb: call pm_runtime_put_noidle " Li Fei
2013-03-01 2:59 ` Li Fei
2013-02-28 8:18 ` [PATCH 3/5] wl1251: call pm_runtime_put_sync " Luciano Coelho
2013-03-05 8:51 ` Luciano Coelho
2013-04-07 10:39 ` [PATCH 2/5] mmc: core: " Ohad Ben-Cohen
2013-04-08 1:36 ` Li, Fei
2013-04-08 1:36 ` [PATCH 2/5 V2] mmc: core: call pm_runtime_put_noidle " Li Fei
2013-04-08 12:48 ` Ohad Ben-Cohen
2013-04-12 18:15 ` Chris Ball
2013-03-01 6:55 ` [PATCH 1/5] regmap: irq: call pm_runtime_put " Mark Brown
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