USB: Reset USB 3.0 devices on (re)discovery
If the device isn't reset, the XHCI HCD sends SET ADDRESS to address 0 while the device is already in Addressed state, and the request is dropped on the floor as it is addressed to the default address. This sequence of events, which this patch fixes looks like this: usb_reset_and_verify_device() hub_port_init() hub_set_address() SET_ADDRESS to 0 with 1 usb_get_device_descriptor(udev, 8) usb_get_device_descriptor(udev, 18) descriptors_changed() --> goto re_enumerate: hub_port_logical_disconnect() kick_khubd() And then: hub_events() hub_port_connect_change() usb_disconnect() usb_disable_device() new device struct sets device state to Powered choose_address() hub_port_init() <-- no reset, but SET ADDRESS to 0 with 1, timeout! The solution is to always reset the device in hub_port_init() to put it in a known state. Note from Sarah Sharp: This patch should be queued for stable trees all the way back to 2.6.34, since that was the first kernel that supported configured device reset. The code this patch touches has been there since 2.6.32, but the bug would never be hit before 2.6.34 because the xHCI driver would completely reject an attempt to reset a configured device under xHCI. Signed-off-by: Luben Tuikov <ltuikov@yahoo.com> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: stable@kernel.org
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