| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame] | 1 | What: /sys/bus/pci/drivers/xhci_hcd/.../dbc |
| 2 | Date: June 2017 |
| 3 | Contact: Lu Baolu <baolu.lu@linux.intel.com> |
| 4 | Description: |
| 5 | xHCI compatible USB host controllers (i.e. super-speed |
| 6 | USB3 controllers) are often implemented with the Debug |
| 7 | Capability (DbC). It can present a debug device which |
| 8 | is fully compliant with the USB framework and provides |
| 9 | the equivalent of a very high performance full-duplex |
| 10 | serial link for debug purpose. |
| 11 | |
| 12 | The DbC debug device shares a root port with xHCI host. |
| 13 | When the DbC is enabled, the root port will be assigned |
| 14 | to the Debug Capability. Otherwise, it will be assigned |
| 15 | to xHCI. |
| 16 | |
| 17 | Writing "enable" to this attribute will enable the DbC |
| 18 | functionality and the shared root port will be assigned |
| 19 | to the DbC device. Writing "disable" to this attribute |
| 20 | will disable the DbC functionality and the shared root |
| 21 | port will roll back to the xHCI. |
| 22 | |
| 23 | Reading this attribute gives the state of the DbC. It |
| 24 | can be one of the following states: disabled, enabled, |
| 25 | initialized, connected, configured and stalled. |