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Date: Tue, 7 Jan 2014 07:25:13 -0800
From: Greg KH <gregkh@linuxfoundation.org>
To: Shen Guang <shenguang10@gmail.com>
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb:hub set hub->change_bits when over-current happens
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On Tue, Jan 07, 2014 at 02:38:36PM +0800, Shen Guang wrote:
> On Tue, Jan 7, 2014 at 11:53 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> > On Tue, Jan 07, 2014 at 11:35:50AM +0800, 沈光 wrote:
> >> On Tue, Jan 7, 2014 at 10:40 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >> > On Tue, Jan 07, 2014 at 10:33:14AM +0800, 沈光 wrote:
> >> >> set hub->change_bits when we plug in a device which causes
> >> >> over-current condition, so that hub_events() will check it.
> >> >
> >> > Why?
> >> >
> >> > What does this solve?  Is this a bug with existing devices that needs to
> >> > be backported to older kernels?
> >> >
> >> > thanks,
> >> >
> >> > greg k-h
> >>
> >> This is something that we found when we are doing compliance test with xHCI.
> >> If we enable CONFIG_USB_SUSPEND, and plug in a bad device which causes
> >> over-current condition to the root port, the hub->change_bits will not
> >> be set in current code in the function of hub_activate.
> >
> > Now that's something that should go in the changelog, don't you think?
> >
> > thanks,
> >
> > greg k-h
> 
> Sure, I agree.
> I am sorry I didn't make it clear enough.
> And the reason why over-current can be detected if CONFIG_USB_SUSPEND
> is disabled, is that the interrupt pipe of the hub will report the
> change and set hub->event_bits, and then hub_events() will check what
> events happened.

Great, care to resend the patch with all of this information added to
it?

thanks,

greg k-h