linux-kernel - Re: [PATCH V2 0/4] introduce device async actions mechanism

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Date:	Wed, 12 Aug 2009 23:18:12 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Zhang Rui <rui.zhang@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-pm" <linux-pm@...ts.linux-foundation.org>,
	"linux-acpi" <linux-acpi@...r.kernel.org>,
	Pavel Machek <pavel@....cz>, Len Brown <lenb@...nel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	"dtor@...l.ru" <dtor@...l.ru>
Subject: Re: [PATCH V2 0/4] introduce device async actions mechanism

On Wednesday 12 August 2009, Alan Stern wrote:
> On Wed, 12 Aug 2009, Rafael J. Wysocki wrote:
> 
> > > The one thing I'm not sure of is the pm_runtime_put_noidle calls in 
> > > driver_probe_device and __device_release_driver.  It seems that we 
> > > should always call pm_runtime_put regardless of whether the probe 
> > > succeeds or not.
> > 
> > Did you mean pm_runtime_put_sync()?
> 
> Yes.  I haven't used the new code yet so the names don't stick in my 
> mind.
> 
> > > For example, the USB stack is set up to suspend devices that don't have
> > > a driver (this is handled at the bus subsystem level).  But if probing
> > > failed, there wouldn't be any idle callback and so the suspend wouldn't
> > > take place.
> > 
> > OK, I'll make this change.
> 
> Thanks.  Now I just have to figure out the best way to convert USB over 
> to the new framework...

:-)

On a second thought, though, would it be a good idea to add
pm_runtime_get_noresume() / pm_runtime_put_sync() around the bus_for_each_drv()
in device_attach()?  That would prevent us from resuming-suspending the device
on each failing probe.

Rafael
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