b41a60eca8
This patch (as920) adds an extra level of protection to the USB-Persist facility. Now it will apply by default only to hubs; for all other devices the user must enable it explicitly by setting the power/persist device attribute. The disconnect_all_children() routine in hub.c has been removed and its code placed inline. This is the way it was originally as part of hub_pre_reset(); the revised usage in hub_reset_resume() is sufficiently different that the code can no longer be shared. Likewise, mark_children_for_reset() is now inline as part of hub_reset_resume(). The end result looks much cleaner than before. The sysfs interface is updated to add the new attribute file, and there are corresponding documentation updates. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
144 lines
5.3 KiB
Text
144 lines
5.3 KiB
Text
#
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# USB Core configuration
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#
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config USB_DEBUG
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bool "USB verbose debug messages"
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depends on USB
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help
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Say Y here if you want the USB core & hub drivers to produce a bunch
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of debug messages to the system log. Select this if you are having a
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problem with USB support and want to see more of what is going on.
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comment "Miscellaneous USB options"
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depends on USB
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config USB_DEVICEFS
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bool "USB device filesystem"
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depends on USB
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---help---
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If you say Y here (and to "/proc file system support" in the "File
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systems" section, above), you will get a file /proc/bus/usb/devices
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which lists the devices currently connected to your USB bus or
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busses, and for every connected device a file named
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"/proc/bus/usb/xxx/yyy", where xxx is the bus number and yyy the
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device number; the latter files can be used by user space programs
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to talk directly to the device. These files are "virtual", meaning
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they are generated on the fly and not stored on the hard drive.
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You may need to mount the usbfs file system to see the files, use
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mount -t usbfs none /proc/bus/usb
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For the format of the various /proc/bus/usb/ files, please read
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<file:Documentation/usb/proc_usb_info.txt>.
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Usbfs files can't handle Access Control Lists (ACL), which are the
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default way to grant access to USB devices for untrusted users of a
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desktop system. The usbfs functionality is replaced by real
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device-nodes managed by udev. These nodes live in /dev/bus/usb and
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are used by libusb.
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config USB_DEVICE_CLASS
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bool "USB device class-devices (DEPRECATED)"
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depends on USB
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default y
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---help---
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Userspace access to USB devices is granted by device-nodes exported
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directly from the usbdev in sysfs. Old versions of the driver
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core and udev needed additional class devices to export device nodes.
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These additional devices are difficult to handle in userspace, if
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information about USB interfaces must be available. One device
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contains the device node, the other device contains the interface
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data. Both devices are at the same level in sysfs (siblings) and one
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can't access the other. The device node created directly by the
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usb device is the parent device of the interface and therefore
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easily accessible from the interface event.
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This option provides backward compatibility for libusb device
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nodes (lsusb) when usbfs is not used, and the following udev rule
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doesn't exist:
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SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", \
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NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0644"
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config USB_DYNAMIC_MINORS
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bool "Dynamic USB minor allocation (EXPERIMENTAL)"
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depends on USB && EXPERIMENTAL
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help
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If you say Y here, the USB subsystem will use dynamic minor
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allocation for any device that uses the USB major number.
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This means that you can have more than 16 of a single type
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of device (like USB printers).
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If you are unsure about this, say N here.
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config USB_SUSPEND
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bool "USB selective suspend/resume and wakeup (EXPERIMENTAL)"
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depends on USB && PM && EXPERIMENTAL
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help
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If you say Y here, you can use driver calls or the sysfs
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"power/state" file to suspend or resume individual USB
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peripherals.
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Also, USB "remote wakeup" signaling is supported, whereby some
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USB devices (like keyboards and network adapters) can wake up
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their parent hub. That wakeup cascades up the USB tree, and
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could wake the system from states like suspend-to-RAM.
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If you are unsure about this, say N here.
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config USB_PERSIST
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bool "USB device persistence during system suspend (DANGEROUS)"
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depends on USB && PM && EXPERIMENTAL
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default n
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help
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If you say Y here and enable the "power/persist" attribute
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for a USB device, the device's data structures will remain
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persistent across system suspend, even if the USB bus loses
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power. (This includes hibernation, also known as swsusp or
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suspend-to-disk.) The devices will reappear as if by magic
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when the system wakes up, with no need to unmount USB
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filesystems, rmmod host-controller drivers, or do anything
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else.
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WARNING: This option can be dangerous!
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If a USB device is replaced by another of the same type while
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the system is asleep, there's a good chance the kernel won't
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detect the change. Likewise if the media in a USB storage
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device is replaced. When this happens it's almost certain to
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cause data corruption and maybe even crash your system.
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If you are unsure, say N here.
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config USB_OTG
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bool
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depends on USB && EXPERIMENTAL
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select USB_SUSPEND
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default n
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config USB_OTG_WHITELIST
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bool "Rely on OTG Targeted Peripherals List"
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depends on USB_OTG
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default y
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help
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If you say Y here, the "otg_whitelist.h" file will be used as a
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product whitelist, so USB peripherals not listed there will be
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rejected during enumeration. This behavior is required by the
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USB OTG specification for all devices not on your product's
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"Targeted Peripherals List".
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Otherwise, peripherals not listed there will only generate a
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warning and enumeration will continue. That's more like what
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normal Linux-USB hosts do (other than the warning), and is
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convenient for many stages of product development.
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config USB_OTG_BLACKLIST_HUB
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bool "Disable external hubs"
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depends on USB_OTG
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help
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If you say Y here, then Linux will refuse to enumerate
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external hubs. OTG hosts are allowed to reduce hardware
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and software costs by not supporting external hubs.
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