1What: /sys/bus/pci/drivers/xhci_hcd/.../dbc 2Date: June 2017 3Contact: Lu Baolu <baolu.lu@linux.intel.com> 4Description: 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. 26 27What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_idVendor 28Date: March 2023 29Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 30Description: 31 This dbc_idVendor attribute lets us change the idVendor field 32 presented in the USB device descriptor by this xhci debug 33 device. 34 Value can only be changed while debug capability (DbC) is in 35 disabled state to prevent USB device descriptor change while 36 connected to a USB host. 37 The default value is 0x1d6b (Linux Foundation). 38 It can be any 16-bit integer. 39 40What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_idProduct 41Date: March 2023 42Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 43Description: 44 This dbc_idProduct attribute lets us change the idProduct field 45 presented in the USB device descriptor by this xhci debug 46 device. 47 Value can only be changed while debug capability (DbC) is in 48 disabled state to prevent USB device descriptor change while 49 connected to a USB host. 50 The default value is 0x0010. It can be any 16-bit integer. 51 52What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_bcdDevice 53Date: March 2023 54Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 55Description: 56 This dbc_bcdDevice attribute lets us change the bcdDevice field 57 presented in the USB device descriptor by this xhci debug 58 device. 59 Value can only be changed while debug capability (DbC) is in 60 disabled state to prevent USB device descriptor change while 61 connected to a USB host. 62 The default value is 0x0010. (device rev 0.10) 63 It can be any 16-bit integer. 64 65What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_bInterfaceProtocol 66Date: March 2023 67Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 68Description: 69 This attribute lets us change the bInterfaceProtocol field 70 presented in the USB Interface descriptor by the xhci debug 71 device. 72 Value can only be changed while debug capability (DbC) is in 73 disabled state to prevent USB descriptor change while 74 connected to a USB host. 75 The default value is 1 (GNU Remote Debug command). 76 Other permissible value is 0 which is for vendor defined debug 77 target. 78 79What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_poll_interval_ms 80Date: February 2024 81Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 82Description: 83 This attribute adjust the polling interval used to check for 84 DbC events. Unit is milliseconds. Accepted values range from 0 85 up to 5000. The default value is 64 ms. 86 This polling interval is used while DbC is enabled but has no 87 active data transfers. 88