Date: Mon, 22 Nov 2010 09:55:23 -0800
From: Greg KH <gregkh@suse.de>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Ben Hutchings <ben@decadent.org.uk>, linux-kernel@vger.kernel.org,
        stable@kernel.org, David Brownell <david-b@pacbell.net>,
        akpm@linux-foundation.org, torvalds@linux-foundation.org,
        stable-review@kernel.org, alan@lxorguk.ukuu.org.uk
Subject: Re: [Stable-review] [39/45] OHCI: work around for nVidia shutdown
 problem
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On Sat, Nov 20, 2010 at 11:51:39AM -0500, Alan Stern wrote:
> On Sat, 20 Nov 2010, Ben Hutchings wrote:
> 
> > On Fri, 2010-11-19 at 13:43 -0800, Greg KH wrote:
> > > 2.6.32-stable review patch.  If anyone has any objections, please let us know.
> > > 
> > > ------------------
> > > 
> > > From: Alan Stern <stern@rowland.harvard.edu>
> > > 
> > > commit 3df7169e73fc1d71a39cffeacc969f6840cdf52b upstream.
> > > 
> > > This patch (as1417) fixes a problem affecting some (or all) nVidia
> > > chipsets.  When the computer is shut down, the OHCI controllers
> > > continue to power the USB buses and evidently they drive a Reset
> > > signal out all their ports.  This prevents attached devices from going
> > > to low power.  Mouse LEDs stay on, for example, which is disconcerting
> > > for users and a drain on laptop batteries.
> > > 
> > > The fix involves leaving each OHCI controller in the OPERATIONAL state
> > > during system shutdown rather than putting it in the RESET state.
> > > Although this nominally means the controller is running, in fact it's
> > > not doing very much since all the schedules are all disabled.  However
> > > there is ongoing DMA to the Host Controller Communications Area, so
> > > the patch also disables the bus-master capability of all PCI USB
> > > controllers after the shutdown routine runs.
> > [...]
> > 
> > This last bit seems like a major change in behaviour, and this commit
> > has only just gone into the 2.6.37 cycle.  How thoroughly has this been
> > tested on other OHCI controllers?  Wouldn't it make more sense to use
> > the same quirk condition?
> 
> Ben is right; let's hold off on putting this patch into any of the 
> stable kernels.  There has been a bug report submitted against it, 
> Bugzilla #22562.

Good point, I'll go drop it.

Alan, when it all gets worked out, care to resend it to
stable@kernel.org?

thanks,

greg k-h
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