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Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd | 46 |
1 files changed, 0 insertions, 46 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd deleted file mode 100644 index 60c60fa624b..00000000000 --- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd +++ /dev/null @@ -1,46 +0,0 @@ -What: /sys/bus/pci/drivers/ehci_hcd/.../companion - /sys/bus/usb/devices/usbN/../companion -Date: January 2007 -KernelVersion: 2.6.21 -Contact: Alan Stern <stern@rowland.harvard.edu> -Description: - PCI-based EHCI USB controllers (i.e., high-speed USB-2.0 - controllers) are often implemented along with a set of - "companion" full/low-speed USB-1.1 controllers. When a - high-speed device is plugged in, the connection is routed - to the EHCI controller; when a full- or low-speed device - is plugged in, the connection is routed to the companion - controller. - - Sometimes you want to force a high-speed device to connect - at full speed, which can be accomplished by forcing the - connection to be routed to the companion controller. - That's what this file does. Writing a port number to the - file causes connections on that port to be routed to the - companion controller, and writing the negative of a port - number returns the port to normal operation. - - For example: To force the high-speed device attached to - port 4 on bus 2 to run at full speed: - - echo 4 >/sys/bus/usb/devices/usb2/../companion - - To return the port to high-speed operation: - - echo -4 >/sys/bus/usb/devices/usb2/../companion - - Reading the file gives the list of ports currently forced - to the companion controller. - - Note: Some EHCI controllers do not have companions; they - may contain an internal "transaction translator" or they - may be attached directly to a "rate-matching hub". This - mechanism will not work with such controllers. Also, it - cannot be used to force a port on a high-speed hub to - connect at full speed. - - Note: When this file was first added, it appeared in a - different sysfs directory. The location given above is - correct for 2.6.35 (and probably several earlier kernel - versions as well). - |