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1What: /sys/bus/pci/drivers/xhci_hcd/.../dbc2Date: June 20173Contact: Lu Baolu <baolu.lu@linux.intel.com>4Description:5 xHCI compatible USB host controllers (i.e. super-speed6 USB3 controllers) are often implemented with the Debug7 Capability (DbC). It can present a debug device which8 is fully compliant with the USB framework and provides9 the equivalent of a very high performance full-duplex10 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 assigned14 to the Debug Capability. Otherwise, it will be assigned15 to xHCI.16 17 Writing "enable" to this attribute will enable the DbC18 functionality and the shared root port will be assigned19 to the DbC device. Writing "disable" to this attribute20 will disable the DbC functionality and the shared root21 port will roll back to the xHCI.22 23 Reading this attribute gives the state of the DbC. It24 can be one of the following states: disabled, enabled,25 initialized, connected, configured and stalled.26 27What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_idVendor28Date: March 202329Contact: Mathias Nyman <mathias.nyman@linux.intel.com>30Description:31 This dbc_idVendor attribute lets us change the idVendor field32 presented in the USB device descriptor by this xhci debug33 device.34 Value can only be changed while debug capability (DbC) is in35 disabled state to prevent USB device descriptor change while36 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_idProduct41Date: March 202342Contact: Mathias Nyman <mathias.nyman@linux.intel.com>43Description:44 This dbc_idProduct attribute lets us change the idProduct field45 presented in the USB device descriptor by this xhci debug46 device.47 Value can only be changed while debug capability (DbC) is in48 disabled state to prevent USB device descriptor change while49 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_bcdDevice53Date: March 202354Contact: Mathias Nyman <mathias.nyman@linux.intel.com>55Description:56 This dbc_bcdDevice attribute lets us change the bcdDevice field57 presented in the USB device descriptor by this xhci debug58 device.59 Value can only be changed while debug capability (DbC) is in60 disabled state to prevent USB device descriptor change while61 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_bInterfaceProtocol66Date: March 202367Contact: Mathias Nyman <mathias.nyman@linux.intel.com>68Description:69 This attribute lets us change the bInterfaceProtocol field70 presented in the USB Interface descriptor by the xhci debug71 device.72 Value can only be changed while debug capability (DbC) is in73 disabled state to prevent USB descriptor change while74 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 debug77 target.78 79What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_poll_interval_ms80Date: February 202481Contact: Mathias Nyman <mathias.nyman@linux.intel.com>82Description:83 This attribute adjust the polling interval used to check for84 DbC events. Unit is milliseconds. Accepted values range from 085 up to 5000. The default value is 64 ms.86 This polling interval is used while DbC is enabled but has no87 active data transfers.88