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author | Jiri Kosina <jkosina@suse.cz> | 2011-11-13 20:55:35 +0100 |
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committer | Jiri Kosina <jkosina@suse.cz> | 2011-11-13 20:55:53 +0100 |
commit | 2290c0d06d82faee87b1ab2d9d4f7bf81ef64379 (patch) | |
tree | e075e4d5534193f28e6059904f61e5ca03958d3c /Documentation/ABI/testing/sysfs-bus-pci-drivers-ehci_hcd | |
parent | 4da669a2e3e5bc70b30a0465f3641528681b5f77 (diff) | |
parent | 52e4c2a05256cb83cda12f3c2137ab1533344edb (diff) | |
download | op-kernel-dev-2290c0d06d82faee87b1ab2d9d4f7bf81ef64379.zip op-kernel-dev-2290c0d06d82faee87b1ab2d9d4f7bf81ef64379.tar.gz |
Merge branch 'master' into for-next
Sync with Linus tree to have 157550ff ("mtd: add GPMI-NAND driver
in the config and Makefile") as I have patch depending on that one.
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, 46 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 0000000..60c60fa --- /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). + |