18c2ecf20Sopenharmony_ciWhat: /sys/bus/pci/drivers/xhci_hcd/.../dbc 28c2ecf20Sopenharmony_ciDate: June 2017 38c2ecf20Sopenharmony_ciContact: Lu Baolu <baolu.lu@linux.intel.com> 48c2ecf20Sopenharmony_ciDescription: 58c2ecf20Sopenharmony_ci xHCI compatible USB host controllers (i.e. super-speed 68c2ecf20Sopenharmony_ci USB3 controllers) are often implemented with the Debug 78c2ecf20Sopenharmony_ci Capability (DbC). It can present a debug device which 88c2ecf20Sopenharmony_ci is fully compliant with the USB framework and provides 98c2ecf20Sopenharmony_ci the equivalent of a very high performance full-duplex 108c2ecf20Sopenharmony_ci serial link for debug purpose. 118c2ecf20Sopenharmony_ci 128c2ecf20Sopenharmony_ci The DbC debug device shares a root port with xHCI host. 138c2ecf20Sopenharmony_ci When the DbC is enabled, the root port will be assigned 148c2ecf20Sopenharmony_ci to the Debug Capability. Otherwise, it will be assigned 158c2ecf20Sopenharmony_ci to xHCI. 168c2ecf20Sopenharmony_ci 178c2ecf20Sopenharmony_ci Writing "enable" to this attribute will enable the DbC 188c2ecf20Sopenharmony_ci functionality and the shared root port will be assigned 198c2ecf20Sopenharmony_ci to the DbC device. Writing "disable" to this attribute 208c2ecf20Sopenharmony_ci will disable the DbC functionality and the shared root 218c2ecf20Sopenharmony_ci port will roll back to the xHCI. 228c2ecf20Sopenharmony_ci 238c2ecf20Sopenharmony_ci Reading this attribute gives the state of the DbC. It 248c2ecf20Sopenharmony_ci can be one of the following states: disabled, enabled, 258c2ecf20Sopenharmony_ci initialized, connected, configured and stalled. 26