# # USB Core configuration # config USB_DEBUG bool "USB verbose debug messages" depends on USB help Say Y here if you want the USB core & hub drivers to produce a bunch of debug messages to the system log. Select this if you are having a problem with USB support and want to see more of what is going on. config USB_ANNOUNCE_NEW_DEVICES bool "USB announce new devices" depends on USB default N help Say Y here if you want the USB core to always announce the idVendor, idProduct, Manufacturer, Product, and SerialNumber strings for every new USB device to the syslog. This option is usually used by distro vendors to help with debugging and to let users know what specific device was added to the machine in what location. If you do not want this kind of information sent to the system log, or have any doubts about this, say N here. comment "Miscellaneous USB options" depends on USB config USB_DEVICEFS bool "USB device filesystem (DEPRECATED)" depends on USB ---help--- If you say Y here (and to "/proc file system support" in the "File systems" section, above), you will get a file /proc/bus/usb/devices which lists the devices currently connected to your USB bus or busses, and for every connected device a file named "/proc/bus/usb/xxx/yyy", where xxx is the bus number and yyy the device number; the latter files can be used by user space programs to talk directly to the device. These files are "virtual", meaning they are generated on the fly and not stored on the hard drive. You may need to mount the usbfs file system to see the files, use mount -t usbfs none /proc/bus/usb For the format of the various /proc/bus/usb/ files, please read <file:Documentation/usb/proc_usb_info.txt>. Modern Linux systems do not use this. Usbfs entries are files and not character devices; usbfs can't handle Access Control Lists (ACL) which are the default way to grant access to USB devices for untrusted users of a desktop system. The usbfs functionality is replaced by real device-nodes managed by udev. These nodes lived in /dev/bus/usb and are used by libusb. config USB_DEVICE_CLASS bool "USB device class-devices (DEPRECATED)" depends on USB default y ---help--- Userspace access to USB devices is granted by device-nodes exported directly from the usbdev in sysfs. Old versions of the driver core and udev needed additional class devices to export device nodes. These additional devices are difficult to handle in userspace, if information about USB interfaces must be available. One device contains the device node, the other device contains the interface data. Both devices are at the same level in sysfs (siblings) and one can't access the other. The device node created directly by the usb device is the parent device of the interface and therefore easily accessible from the interface event. This option provides backward compatibility for libusb device nodes (lsusb) when usbfs is not used, and the following udev rule doesn't exist: SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", \ NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0644" config USB_DYNAMIC_MINORS bool "Dynamic USB minor allocation" depends on USB help If you say Y here, the USB subsystem will use dynamic minor allocation for any device that uses the USB major number. This means that you can have more than 16 of a single type of device (like USB printers). If you are unsure about this, say N here. config USB_SUSPEND bool "USB runtime power management (autosuspend) and wakeup" depends on USB && PM_RUNTIME help If you say Y here, you can use driver calls or the sysfs "power/control" file to enable or disable autosuspend for individual USB peripherals (see Documentation/usb/power-management.txt for more details). Also, USB "remote wakeup" signaling is supported, whereby some USB devices (like keyboards and network adapters) can wake up their parent hub. That wakeup cascades up the USB tree, and could wake the system from states like suspend-to-RAM. If you are unsure about this, say N here. config USB_OTG bool "OTG support" depends on USB && EXPERIMENTAL depends on USB_SUSPEND default n help The most notable feature of USB OTG is support for a "Dual-Role" device, which can act as either a device or a host. The initial role is decided by the type of plug inserted and can be changed later when two dual role devices talk to each other. Select this only if your board has Mini-AB/Micro-AB connector. config USB_OTG_WHITELIST bool "Rely on OTG Targeted Peripherals List" depends on USB_OTG || EXPERT default y if USB_OTG default n if EXPERT help If you say Y here, the "otg_whitelist.h" file will be used as a product whitelist, so USB peripherals not listed there will be rejected during enumeration. This behavior is required by the USB OTG specification for all devices not on your product's "Targeted Peripherals List". "Embedded Hosts" are likewise allowed to support only a limited number of peripherals. Otherwise, peripherals not listed there will only generate a warning and enumeration will continue. That's more like what normal Linux-USB hosts do (other than the warning), and is convenient for many stages of product development. config USB_OTG_BLACKLIST_HUB bool "Disable external hubs" depends on USB_OTG || EXPERT help If you say Y here, then Linux will refuse to enumerate external hubs. OTG hosts are allowed to reduce hardware and software costs by not supporting external hubs. So are "Embedded Hosts" that don't offer OTG support.