linux-kernel - Re: [34-stable regression] USB delay init quirk causes device events loss

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Message-ID: <Pine.LNX.4.44L0.1009141001220.1648-100000@iolanthe.rowland.org>
Date:	Tue, 14 Sep 2010 10:03:29 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Oliver Neukum <oneukum@...e.de>
cc:	Jiri Slaby <jslaby@...e.cz>, <phil@...m.com>, <stable@...nel.org>,
	Greg KH <gregkh@...e.de>, USB list <linux-usb@...r.kernel.org>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [34-stable regression] USB delay init quirk causes device events
 loss

On Tue, 14 Sep 2010, Oliver Neukum wrote:

> Am Montag, 13. September 2010, 17:37:49 schrieb Alan Stern:
> > Okay, I see the problem.  By moving usb_detect_quirks earlier, we end 
> > up calling usb_disable_autosuspend too soon -- before the 
> > pm_runtime_enable call in usb_new_device.  In 2.6.35 this doesn't 
> > matter because the implementation of usb_autosuspend_device has 
> > changed.
> > 
> > So yes, in the end it looks like the best course is to revert this
> > patch from 2.6.34.stable.  This is unfortunate but I don't see any way
> > around it without making changes that aren't present in the current
> > kernel. For example, the pm_runtime_set_active and pm_runtime_enable
> > calls could also be moved from usb_new_device into
> > hub_port_connect_change.
> 
> Calling usb_detect_quirks() twice?

The issue is moot now since Greg has already done the reversion.

But no, usb_detect_quirks should still be called only once.  The idea 
was to make sure this happens _after_ pm_runtime_set_active and 
pm_runtime_enable, by moving those two calls earlier.

Alan Stern

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