linux-imx

usb: Don't disable Latency tolerance Messaging (LTM) before port reset

Disabing Latency Tolerance Messaging before port reset is unnecessary.
LTM is automatically disabled at port reset.

If host can't communicate with the device the LTM message will fail, and
the hub driver will unnecessarily do a logical disconnect.
Broken communication is ofter the reason for a reset in the first place.

Additionally we can't guarantee device is in a configured state,
epecially in reset-resume case when root hub lost power.
LTM can't be modified unless device is in a configured state.

Just remove LTM disabling before port reset.

Details about LTM and port reset in USB 3 specification:

USB 3 spec section 9.4.5
"The LTM Enable field can be modified by the SetFeature() and
ClearFeature() requests using the LTM_ENABLE feature selector.
This field is reset to zero when the device is reset."

USB 3 spec section 9.4.1
"The device shall process a Clear Feature (U1_Enable or U2_Enable or
LTM_Enable) only if the device is in the configured state."

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>