From 25aa55488c3644b19e33ba79c564191b8e33f477 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Wed, 14 Sep 2011 12:33:16 -0400 Subject: USB: document ehci-hcd's "companion" sysfs attribute This patch (as1484) adds documentation for ehci-hcd's "companion" sysfs attribute, which was added to the kernel over four years ago but never documented. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- .../ABI/testing/sysfs-bus-pci-drivers-ehci_hcd | 46 ++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd (limited to 'Documentation/ABI/testing') 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 +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). + -- cgit v1.2.1 From c1045e87b2cd293d53dff19779ea46b19195d593 Mon Sep 17 00:00:00 2001 From: Andiry Xu Date: Fri, 23 Sep 2011 14:19:53 -0700 Subject: usbcore: add sysfs support to xHCI usb2 hardware LPM This patch adds sysfs support to xHCI usb2 hardware LPM, so developer can enable and disable usb2 hardware LPM manually for test purpose. Signed-off-by: Andiry Xu Signed-off-by: Sarah Sharp Signed-off-by: Greg Kroah-Hartman --- Documentation/ABI/testing/sysfs-bus-usb | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'Documentation/ABI/testing') 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 +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. -- cgit v1.2.1