option to ignore flash memory device at USB1.1 "full" speed

John Reiser jreiser at bitwagon.com
Sat Jun 15 15:24:33 UTC 2013


How can I force the system not to recognize a USB2.0 flash memory device at USB1.1 speed?

A couple times per month I plug in a USB2.0 flash memory stick,
but it gets recognized as a 12 megabits/second USB1.1 device:

  kernel: [sss,uuu] usb 5-1: new full-speed USB device number 2 using ohci_hcd

instead of as a 480 megabits/second USB2.0 device:

  kernel: [sss.uuu] usb 5-1: new high-speed USB device number 2 using ehci_hcd

Unfortunately 12Mb/s "works" very slowly.  It can take a long time (many tens of
seconds) after killing the application that initiated the writes before the kernel
finishes pending operations, thus enabling safe removal of the device.
Usually unplugging and re-plugging the flash memory stick (perhaps into a different
port) is enough to achieve recognition as a USB2.0 device.

So, I would like to restrict flash memory devices to USB2.0 (or USB3).  How?
It would be nice if a true USB1.1 device (such as mouse or keyboard) still worked.
Perhaps the "USB2.0 only" restriction could be on specific ports, although it
would be best if based on device type instead of by port.

-- 




More information about the devel mailing list