linux-kernel - Re: [PATCH] PM: use pm_op methods for device types

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Message-ID: <Pine.LNX.4.44L0.0809260948580.2395-100000@iolanthe.rowland.org>
Date:	Fri, 26 Sep 2008 09:56:55 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Greg KH <greg@...ah.com>, "Rafael J. Wysocki" <rjw@...k.pl>
cc:	Hannes Reinecke <hare@...e.de>, Kay Sievers <kay.sievers@...y.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Slaby <jirislaby@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux-pm mailing list <linux-pm@...ts.linux-foundation.org>,
	USB list <linux-usb@...r.kernel.org>
Subject: Re: [PATCH] PM: use pm_op methods for device types

On Thu, 25 Sep 2008, Greg KH wrote:

> On Thu, Sep 25, 2008 at 11:27:02PM +0200, Rafael J. Wysocki wrote:
> > On Thursday, 25 of September 2008, Alan Stern wrote:
> > > This patch (as1141) adds code to use the device type's pm_op methods,
> > > if they are defined.  It fixes a regression in the USB PM code; the
> > > various suspend and resume methods are defined in the device type
> > > rather than in the bus, because USB devices have to be handled
> > > differently from USB interfaces.  Without the patch, those methods
> > > never get called.
> > > 
> > > The patch also fixes a couple of spelling errors.
> > 
> > Hm, these changes are not needed in the current mainline, so there's a patch
> > in -next that removes the code added by this patch.
> > 
> > It might be better to find that patch and drop it instead, IMO.
> 
> I agree, I think we would have seen more bugs if mainline can't suspend
> with a USB device attached, right?
> 
> confused,

Okay, I was confused too.  Looking more closely, it's apparent that 
mainline is okay and the problem was introduced by Hannes Reinecke's 

driver-core-remove-suspend-resume-callbacks-for-device-type.patch

which states that the suspend/resume callbacks in struct device_type
are unused.  It may be true that the legacy suspend/resume methods are
unused, but the new pm_ops methods definitely are used.

Therefore part or all of Hannes patch should be reverted.  And the 
mainline is okay as it stands.

Alan Stern

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