diff options
Diffstat (limited to 'Documentation/ABI/testing')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd | 46 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 15 |
2 files changed, 61 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd new file mode 100644 index 000000000000..60c60fa624b2 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd @@ -0,0 +1,46 @@ +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). + diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 294aa864a60a..e647378e9e88 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -142,3 +142,18 @@ Description: such devices. Users: usb_modeswitch + +What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm +Date: September 2011 +Contact: Andiry Xu <andiry.xu@amd.com> +Description: + If CONFIG_USB_SUSPEND is set and a USB 2.0 lpm-capable device + is plugged in to a xHCI host which support link PM, it will + perform a LPM test; if the test is passed and host supports + USB2 hardware LPM (xHCI 1.0 feature), USB2 hardware LPM will + be enabled for the device and the USB device directory will + contain a file named power/usb2_hardware_lpm. The file holds + a string value (enable or disable) indicating whether or not + USB2 hardware LPM is enabled for the device. Developer can + write y/Y/1 or n/N/0 to the file to enable/disable the + feature. |