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RE: [PATCH] usb:solve resume usb device identification problem

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Hi,
> -----Original Message-----
> From: Alan Stern [mailto:stern@rowland.harvard.edu]
> Sent: Monday, July 11, 2016 10:51 PM
> To: Lipengcheng
> Cc: gregkh@linuxfoundation.org; baolu.lu@linux.intel.com; chasemetzger15@gmail.com; mathias.nyman@linux.intel.com;
> oneukum@suse.com; jun.li@freescale.com; linux-usb@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] usb:solve resume usb device identification problem
> 
> On Mon, 11 Jul 2016, Pengcheng Li wrote:
> 
> > A usb device in the connection state. Then host is suspend and resume.
> > But the usb device could not be at the right speed. We should be reset
> > the reset.
> >
> > Signed-off-by: Pengcheng Li <lpc.li@hisilicon.com>
> 
> Why wouldn't the USB device be at the right speed?
> 
For example, some USB3 devices are resume, the device may be in USB 2.0 Device States. We should have USB 2.0 reset and
make the device into the right speed.
 
> You should _not_ reset the device if it is at the right speed.
>
> > @@ -3512,6 +3512,10 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
> >  		}
> >  	}
> >
> > +	retval = hub_port_reset(hub, port1, udev, HUB_ROOT_RESET_TIME, false);
> > +	if (retval < 0)
> > +		hub_port_disable(hub, port1, 0);
> > +
> 
> Most of the time (for example, for non-USB3 devices) this would be wrong.
> 
Yes, USB3 devices have this problem. So far, USB2 device can not find this problem. 
I mainly refer to the reset process of usb enumeration process.
> Alan Stern

Thanks,
Pengcheng Li

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Thread

[PATCH] usb:solve resume usb device identification problem Pengcheng Li <lpc.li@hisilicon.com> - 2016-07-11 15:10 +0200
  Re: [PATCH] usb:solve resume usb device identification problem Alan Stern <stern@rowland.harvard.edu> - 2016-07-11 17:00 +0200
    RE: [PATCH] usb:solve resume usb device identification problem Lipengcheng <lpc.li@hisilicon.com> - 2016-07-12 03:50 +0200
  Re: [PATCH] usb:solve resume usb device identification problem Lu Baolu <baolu.lu@linux.intel.com> - 2016-07-12 02:50 +0200
    RE: [PATCH] usb:solve resume usb device identification problem Lipengcheng <lpc.li@hisilicon.com> - 2016-07-12 04:00 +0200
      Re: [PATCH] usb:solve resume usb device identification problem Lu Baolu <baolu.lu@linux.intel.com> - 2016-07-12 04:30 +0200
        RE: [PATCH] usb:solve resume usb device identification problem Lipengcheng <lpc.li@hisilicon.com> - 2016-07-12 13:40 +0200

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