1*dfba2174SLu BaoluWhat: /sys/bus/pci/drivers/xhci_hcd/.../dbc 2*dfba2174SLu BaoluDate: June 2017 3*dfba2174SLu BaoluContact: Lu Baolu <baolu.lu@linux.intel.com> 4*dfba2174SLu BaoluDescription: 5*dfba2174SLu Baolu xHCI compatible USB host controllers (i.e. super-speed 6*dfba2174SLu Baolu USB3 controllers) are often implemented with the Debug 7*dfba2174SLu Baolu Capability (DbC). It can present a debug device which 8*dfba2174SLu Baolu is fully compliant with the USB framework and provides 9*dfba2174SLu Baolu the equivalent of a very high performance full-duplex 10*dfba2174SLu Baolu serial link for debug purpose. 11*dfba2174SLu Baolu 12*dfba2174SLu Baolu The DbC debug device shares a root port with xHCI host. 13*dfba2174SLu Baolu When the DbC is enabled, the root port will be assigned 14*dfba2174SLu Baolu to the Debug Capability. Otherwise, it will be assigned 15*dfba2174SLu Baolu to xHCI. 16*dfba2174SLu Baolu 17*dfba2174SLu Baolu Writing "enable" to this attribute will enable the DbC 18*dfba2174SLu Baolu functionality and the shared root port will be assigned 19*dfba2174SLu Baolu to the DbC device. Writing "disable" to this attribute 20*dfba2174SLu Baolu will disable the DbC functionality and the shared root 21*dfba2174SLu Baolu port will roll back to the xHCI. 22*dfba2174SLu Baolu 23*dfba2174SLu Baolu Reading this attribute gives the state of the DbC. It 24*dfba2174SLu Baolu can be one of the following states: disabled, enabled, 25*dfba2174SLu Baolu initialized, connected, configured and stalled. 26