linux-kernel - RE: [PATCH] usb:solve resume usb device identification problem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 12 Jul 2016 01:45:29 +0000
From:	Lipengcheng <lpc.li@...ilicon.com>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
	"chasemetzger15@...il.com" <chasemetzger15@...il.com>,
	"mathias.nyman@...ux.intel.com" <mathias.nyman@...ux.intel.com>,
	"oneukum@...e.com" <oneukum@...e.com>,
	"jun.li@...escale.com" <jun.li@...escale.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] usb:solve resume usb device identification problem


Hi,
> -----Original Message-----
> From: Alan Stern [mailto:stern@...land.harvard.edu]
> Sent: Monday, July 11, 2016 10:51 PM
> To: Lipengcheng
> Cc: gregkh@...uxfoundation.org; baolu.lu@...ux.intel.com; chasemetzger15@...il.com; mathias.nyman@...ux.intel.com;
> oneukum@...e.com; jun.li@...escale.com; linux-usb@...r.kernel.org; linux-kernel@...r.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@...ilicon.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