• Guoqing Zhang's avatar
    usb: xhci: Add port test modes support for usb2. · 0f1d832e
    Guoqing Zhang authored
    For usb2 ports, the port test mode Test_J_State, Test_K_State,
    Test_Packet, Test_SE0_NAK and Test_Force_En can be enabled
    as described in usb2 spec.
    
    USB2 test mode is a required hardware feature for system integrators
    validating their hardware according to USB spec, regarding signal
    strength and stuff. It is purely a hardware test feature.
    
    Usually you need an oscilloscope and have to enable those test modes on
    the hardware. This will send some specific test patterns on D+/D-. There
    is no report available (in Linux itself) as it is purely externally
    visible. Regular USB usage is not possible at that time.
    Anyone (well access to e.g. /dev/bus/usb/001/001 provided) can use it by
    sending appropriate USB_PORT_FEAT_TEST requests to the hub.
    
    [Add better commit message by Alexander Stein  -Mathias]
    Signed-off-by: default avatarGuoqing Zhang <guoqing.zhang@intel.com>
    Cc: Alexander Stein <alexander.stein@systec-electronic.com>
    Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    0f1d832e
xhci-hub.c 46.5 KB