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| author | Mathias Nyman <mathias.nyman@linux.intel.com> | 2023-03-17 16:47:09 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-23 17:25:22 +0100 |
| commit | edf1664f3249a091a2b91182fc087b3253b0b4c2 (patch) | |
| tree | 918498c17a1bc58093dac442d4429dc04ee3b802 /Documentation | |
| parent | xhci: mem: Join string literals back (diff) | |
| download | linux-edf1664f3249a091a2b91182fc087b3253b0b4c2.tar.xz linux-edf1664f3249a091a2b91182fc087b3253b0b4c2.zip | |
xhci: dbc: Provide sysfs option to configure dbc descriptors
When DbC is enabled the first port on the xHC host acts as a usb device.
xHC provides the descriptors automatically when the DbC device is
enumerated. Most of the values are hardcoded, but some fields such as
idProduct, idVendor, bcdDevice and bInterfaceProtocol can be modified.
Add sysfs entries that allow userspace to change these.
User can only change them before dbc is enabled, i.e. before writing
"enable" to dbc sysfs file as we don't want these values to change while
device is connected, or during enumeration.
Add documentation for these entries in
Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20230317154715.535523-9-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd index 0088aba4caa8..5a775b8f6543 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd +++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd @@ -23,3 +23,55 @@ Description: Reading this attribute gives the state of the DbC. It can be one of the following states: disabled, enabled, initialized, connected, configured and stalled. + +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_idVendor +Date: March 2023 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + This dbc_idVendor attribute lets us change the idVendor field + presented in the USB device descriptor by this xhci debug + device. + Value can only be changed while debug capability (DbC) is in + disabled state to prevent USB device descriptor change while + connected to a USB host. + The default value is 0x1d6b (Linux Foundation). + It can be any 16-bit integer. + +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_idProduct +Date: March 2023 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + This dbc_idProduct attribute lets us change the idProduct field + presented in the USB device descriptor by this xhci debug + device. + Value can only be changed while debug capability (DbC) is in + disabled state to prevent USB device descriptor change while + connected to a USB host. + The default value is 0x0010. It can be any 16-bit integer. + +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_bcdDevice +Date: March 2023 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + This dbc_bcdDevice attribute lets us change the bcdDevice field + presented in the USB device descriptor by this xhci debug + device. + Value can only be changed while debug capability (DbC) is in + disabled state to prevent USB device descriptor change while + connected to a USB host. + The default value is 0x0010. (device rev 0.10) + It can be any 16-bit integer. + +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_bInterfaceProtocol +Date: March 2023 +Contact: Mathias Nyman <mathias.nyman@linux.intel.com> +Description: + This attribute lets us change the bInterfaceProtocol field + presented in the USB Interface descriptor by the xhci debug + device. + Value can only be changed while debug capability (DbC) is in + disabled state to prevent USB descriptor change while + connected to a USB host. + The default value is 1 (GNU Remote Debug command). + Other permissible value is 0 which is for vendor defined debug + target. |