Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) What:		/sys/bus/pci/drivers/ehci_hcd/.../companion
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) 		/sys/bus/usb/devices/usbN/../companion
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) Date:		January 2007
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) KernelVersion:	2.6.21
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) Contact:	Alan Stern <stern@rowland.harvard.edu>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) Description:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) 		PCI-based EHCI USB controllers (i.e., high-speed USB-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) 		controllers) are often implemented along with a set of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) 		"companion" full/low-speed USB-1.1 controllers.  When a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 		high-speed device is plugged in, the connection is routed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 		to the EHCI controller; when a full- or low-speed device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) 		is plugged in, the connection is routed to the companion
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 		controller.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 		Sometimes you want to force a high-speed device to connect
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 		at full speed, which can be accomplished by forcing the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 		connection to be routed to the companion controller.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 		That's what this file does.  Writing a port number to the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 		file causes connections on that port to be routed to the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 		companion controller, and writing the negative of a port
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 		number returns the port to normal operation.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 		For example: To force the high-speed device attached to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 		port 4 on bus 2 to run at full speed::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 			echo 4 >/sys/bus/usb/devices/usb2/../companion
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 		To return the port to high-speed operation::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 			echo -4 >/sys/bus/usb/devices/usb2/../companion
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 		Reading the file gives the list of ports currently forced
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 		to the companion controller.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 		Note: Some EHCI controllers do not have companions; they
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 		may contain an internal "transaction translator" or they
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 		may be attached directly to a "rate-matching hub".  This
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 		mechanism will not work with such controllers.  Also, it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 		cannot be used to force a port on a high-speed hub to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 		connect at full speed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 		Note: When this file was first added, it appeared in a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 		different sysfs directory.  The location given above is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 		correct for 2.6.35 (and probably several earlier kernel
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 		versions as well).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46)