Messages in this thread |  | | Date | Sat, 12 Jan 2013 12:37:33 -0500 (EST) | From | Alan Stern <> | Subject | Re: USB device cannot be reconnected and khubd "blocked for more than 120 seconds" |
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On Sat, 12 Jan 2013, Alex Riesen wrote:
> On Fri, Jan 11, 2013 at 10:04 PM, Alex Riesen <raa.lkml@gmail.com> wrote: > > Hi, > > > > the USB stick (an Cruzer Titanium 2GB) was not recognized at any of > > the USB ports of this system (an System76 lemu4 laptop, XHCI device) > > after it was removed. If I attempt to insert it again in any of the > > ports (one of the two USB3, or the USB2) the led on the stick lights > > up shortly and if off again. There is no media detection messages in > > the dmesg output, only that from the first time:
To make testing simpler, use only the USB-2 ports. The xHCI driver is not as mature as the EHCI driver.
> > usb 1-1.2: new high-speed USB device number 3 using ehci-pci > > usb 1-1.2: New USB device found, idVendor=0781, idProduct=5408 > > usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 > > usb 1-1.2: Product: U3 Titanium > > usb 1-1.2: Manufacturer: SanDisk Corporation > > usb 1-1.2: SerialNumber: 0000187A3A60F1E9 > > scsi6 : usb-storage 1-1.2:1.0 > > io scheduler deadline registered (default) > > usb 1-1.2: USB disconnect, device number 3 > > > > The kernel is v3.8-rc3. I never had this problem in 3.7. I could almost > > reproduce the problem later in a simplified setup (init=/bin/bash) on > > USB3 ports by inserting and removing the stick quickly. Almost - because > > the USB3 ports recovered after some time, while the USB2 port never > > experienced the problem.
For testing, use a kernel with CONFIG_USB_DEBUG and CONFIG_PRINTK_TIME enabled. Do the following:
After a normal boot, run "dmesg -C" to clear the log buffer.
Then plug in the stick. After a couple of seconds, type Alt-SysRq-W.
Then unplug the stick. After a couple of seconds, type Alt-SysRq-W again.
Then collect the output from dmesg and post it.
> One more detail: I usually use the "noop" elevator. That time it was > the "deadline". And I just reproduced it easily with "deadline".
I doubt the elevator has anything to do with this.
Alan Stern
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