From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: "Huang Ying" <ying.huang@intel.com>, "Bjørn Mork" <bjorn@mork.no>,
"huang ying" <huang.ying.caritas@gmail.com>,
"Zheng Yan" <zheng.z.yan@intel.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
linux-pci@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: bisected regression, v3.5 -> next-20120724: PCI PM causes USB hotplug failure
Date: Sat, 28 Jul 2012 22:26:40 +0200 [thread overview]
Message-ID: <201207282226.40306.rjw@sisk.pl> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1207281208050.23545-100000@netrider.rowland.org>
On Saturday, July 28, 2012, Alan Stern wrote:
> On Fri, 27 Jul 2012, Rafael J. Wysocki wrote:
>
> > > > > > + if (parent)
> > > > > > + pm_runtime_put(parent);
> > > > >
> > > > > You should use pm_runtime_put_sync(), not pm_runtime_put().
> > > >
> > > > Hmm, why exactly?
> > >
> > > Because it's more efficient to do something directly than to run it in
> > > a workqueue.
> >
> > Well, depends. If that results in a power off (the parent goes into
> > D3 for example), we may wait as long as 10 ms for that to complete.
>
> True, but so what? You'd also have to wait 10 ms for the workqueue
> item to complete if pm_runtime_put() was used,
Are you sure? pm_runtime_put() leads to rpm_idle() with the RPM_ASYNC
flag set, which causes it to queue up the work item and return immediately
without waiting. Why exactly do you think I'd need to wait, then?
> plus the additional overhead of scheduling the workqueue thread.
>
> Now, if the length of time required for the probe to run were an issue
> then yes, the synchronous routine could make things take longer. But
> probing is generally done asynchronously anyway, right? And usually
> what matters is the time before the device becomes available, not the
> time for the probe to run.
Still, I see no reason to wait synchronously for the _parent_ to suspend.
Thanks,
Rafael
next prev parent reply other threads:[~2012-07-28 20:20 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.44L0.1207241312050.1164-100000@iolanthe.rowland.org>
[not found] ` <87r4s0opck.fsf@nemi.mork.no>
2012-07-25 4:08 ` bisected regression, v3.5 -> next-20120724: PCI PM causes USB hotplug failure Bjørn Mork
2012-07-25 4:34 ` Huang Ying
2012-07-25 9:58 ` Bjørn Mork
2012-07-25 13:30 ` huang ying
2012-07-25 13:58 ` Bjørn Mork
2012-07-25 18:56 ` Rafael J. Wysocki
2012-07-25 20:02 ` Rafael J. Wysocki
2012-07-25 22:36 ` Bjørn Mork
2012-07-26 2:38 ` Huang Ying
2012-07-26 2:38 ` Huang Ying
2012-07-26 8:54 ` Huang Ying
2012-07-26 10:35 ` Bjørn Mork
2012-07-26 11:02 ` Bjørn Mork
2012-07-26 12:04 ` Bjørn Mork
2012-07-26 15:03 ` Alan Stern
2012-07-26 16:24 ` Bjørn Mork
2012-07-27 5:35 ` Huang Ying
2012-07-27 9:11 ` Bjørn Mork
2012-07-30 3:15 ` Huang Ying
2012-07-30 8:08 ` Bjørn Mork
2012-07-30 13:31 ` huang ying
2012-07-30 16:57 ` Bjørn Mork
2012-07-31 0:22 ` Huang Ying
2012-07-30 14:19 ` Alan Stern
2012-07-31 0:24 ` Huang Ying
2012-07-31 3:18 ` Huang Ying
2012-07-31 17:07 ` Alan Stern
2012-07-27 15:03 ` Alan Stern
2012-07-27 19:11 ` Rafael J. Wysocki
2012-07-27 19:39 ` Alan Stern
2012-07-27 19:54 ` Rafael J. Wysocki
2012-07-28 16:12 ` Alan Stern
2012-07-28 20:26 ` Rafael J. Wysocki [this message]
2012-07-28 21:12 ` Alan Stern
2012-07-29 13:55 ` Rafael J. Wysocki
2012-07-29 14:55 ` Alan Stern
2012-07-29 19:18 ` Rafael J. Wysocki
2012-07-31 20:31 ` Do we need asynchronous pm_runtime_get()? (was: Re: bisected regression ...) Rafael J. Wysocki
2012-07-31 21:05 ` Alan Stern
2012-07-31 21:34 ` Rafael J. Wysocki
2012-07-31 21:49 ` Rafael J. Wysocki
2012-08-01 14:36 ` Alan Stern
2012-08-01 21:24 ` Rafael J. Wysocki
2012-08-02 20:16 ` Alan Stern
2012-08-02 21:26 ` Rafael J. Wysocki
2012-08-03 2:20 ` Alan Stern
2012-08-03 3:37 ` Ming Lei
2012-08-03 14:28 ` Alan Stern
2012-08-04 19:47 ` Rafael J. Wysocki
2012-08-04 20:25 ` Alan Stern
2012-08-04 20:48 ` Rafael J. Wysocki
2012-08-04 20:48 ` Alan Stern
2012-08-04 21:15 ` Rafael J. Wysocki
2012-08-04 22:13 ` Alan Stern
2012-08-05 15:26 ` Rafael J. Wysocki
2012-08-06 13:30 ` Ming Lei
2012-08-06 14:47 ` Alan Stern
2012-08-07 1:35 ` Ming Lei
2012-08-07 11:23 ` Rafael J. Wysocki
2012-08-07 15:14 ` Ming Lei
2012-08-07 15:42 ` Alan Stern
2012-08-07 16:30 ` Ming Lei
2012-08-07 20:57 ` Rafael J. Wysocki
2012-08-07 20:45 ` Rafael J. Wysocki
2012-08-08 2:02 ` Ming Lei
2012-08-08 18:42 ` Alan Stern
2012-08-08 20:16 ` Rafael J. Wysocki
2012-08-09 5:55 ` Ming Lei
2012-08-09 10:46 ` Rafael J. Wysocki
2012-08-09 10:55 ` Ming Lei
2012-08-09 19:41 ` Rafael J. Wysocki
2012-08-10 3:19 ` Ming Lei
2012-08-10 20:29 ` Rafael J. Wysocki
2012-08-08 22:27 ` Rafael J. Wysocki
2012-08-06 15:48 ` Alan Stern
2012-08-06 20:30 ` Rafael J. Wysocki
2012-08-07 12:28 ` Rafael J. Wysocki
2012-08-07 17:15 ` Alan Stern
2012-08-07 21:31 ` Rafael J. Wysocki
2012-08-03 14:05 ` Alan Stern
2012-08-04 20:08 ` Rafael J. Wysocki
2012-08-04 20:42 ` Alan Stern
2012-08-04 20:59 ` Rafael J. Wysocki
2012-08-04 19:35 ` Rafael J. Wysocki
2012-07-29 20:12 ` bisected regression, v3.5 -> next-20120724: PCI PM causes USB hotplug failure Jassi Brar
2012-07-29 21:44 ` Alan Stern
2012-07-25 19:51 ` [PATCH] PCI / PM: Fix messages printed by acpi_pci_set_power_state() Rafael J. Wysocki
2012-07-25 20:02 ` Alan Stern
2012-07-25 20:48 ` [PATCH][update] " Rafael J. Wysocki
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