linux-kernel - Re: [lkp] [PM / sleep] 013c074f86: [drm:intel_opregion_init [i915]] *ERROR* No ACPI video bus found

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Date:	Tue, 12 Jan 2016 12:25:09 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Grygorii Strashko <grygorii.strashko@...com>,
	kernel test robot <ying.huang@...ux.intel.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, lkp@...org,
	LKML <linux-kernel@...r.kernel.org>, Pavel Machek <pavel@....cz>,
	Alan Stern <stern@...land.harvard.edu>,
	linux-input@...r.kernel.org
Subject: Re: [lkp] [PM / sleep] 013c074f86: [drm:intel_opregion_init [i915]]
 *ERROR* No ACPI video bus found

On Tue, Jan 12, 2016 at 09:11:15PM +0100, Rafael J. Wysocki wrote:
> On Tuesday, January 12, 2016 08:38:57 PM Grygorii Strashko wrote:
> > Hi All,
> > 
> > Cc: more people + linux-input@...r.kernel.org
> > 
> > On 01/07/2016 03:49 AM, kernel test robot wrote:
> > > FYI, we noticed the below changes on
> > > 
> > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > > commit 013c074f8642d8e815ad670601f8e27155a74b57 ("PM / sleep: prohibit devices probing during suspend/hibernation")
> > > 
> > > <4>[   33.021805] serio serio0: device_attach() failed for isa0060/serio0 (i8042 KBD port), error: -517
> > > <4>[   33.021813] serio serio1: device_attach() failed for isa0060/serio1 (i8042 AUX port), error: -517
> > > <6>[   33.021906] PM: resume of devices complete after 171.688 msecs
> > > 
> > > To reproduce:
> > > 
> > >          git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
> > >          cd lkp-tests
> > >          bin/lkp install job.yaml  # job file is attached in this email
> > >          bin/lkp run     job.yaml
> > 
> > I've done some investigation of the above log output:
> > 1) Small introduction first: commit 013c074f8642 was created, because it was identified
> > that it's unsafe to bind/probe drivers during suspend resume, mainly because this will
> > cause changing of pointers on PM data structures on the fly for devices which already
> > tracked by Suspend core.
> > 
> > 2) above log prints can be generated by the below call chain (I've checked the code only):
> > 
> > drivers/input/serio/serio.c
> > serio_resume()
> >  - serio_queue_event(serio, NULL, SERIO_RECONNECT_PORT)
> >    - queue_work(system_long_wq, &serio_event_work);
> >  ....
> >  - serio_handle_event()
> >    - serio_reconnect_port()
> > 	- serio_reconnect_driver() --- return <0

Any chance you could track why serio_reconnect_driver returns error
here? Ideally it should have succeeded.

> > 		
> > 	- serio_disconnect_port()
> > 	  - device_release_driver() --- unbind
> >  	- serio_find_driver()
> > 	   error = device_attach(&serio->dev);
> > 	   if (error < 0)
> > 		dev_warn(&serio->dev,
> > 			 "device_attach() failed for %s (%s), error: %d\n",
> > 			 serio->phys, serio->name, error);
> > 
> >   device_attach() will return -EPROBE_DEFER(-517) because the device probing is not allowed yet.
> > 
> > As per my understanding (and it's not clear from issue description), above situation
> > should not break functionality of the system - just device's probe will be delayed till the
> > end of dpm_complete(). So, I propose consider the option - do not print above warnings if 
> > return code from device_attach() is -EPROBE_DEFER.
> 
> This looks like a reasonable thing to do to me.

Looks like it will work.

Thanks.

-- 
Dmitry