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usb_make_path(9) [centos man page]

USB_MAKE_PATH(9)					  Host-Side Data Types and Macro					  USB_MAKE_PATH(9)

usb_make_path - returns stable device path in the usb tree SYNOPSIS
int usb_make_path(struct usb_device * dev, char * buf, size_t size); ARGUMENTS
dev the device whose path is being constructed buf where to put the string size how big is "buf"? RETURN
Length of the string (> 0) or negative if size was too small. NOTE
This identifier is intended to be "stable", reflecting physical paths in hardware such as physical bus addresses for host controllers or ports on USB hubs. That makes it stay the same until systems are physically reconfigured, by re-cabling a tree of USB devices or by moving USB host controllers. Adding and removing devices, including virtual root hubs in host controller driver modules, does not change these path identifiers; neither does rebooting or re-enumerating. These are more useful identifiers than changeable ("unstable") ones like bus numbers or device addresses. With a partial exception for devices connected to USB 2.0 root hubs, these identifiers are also predictable. So long as the device tree isn't changed, plugging any USB device into a given hub port always gives it the same path. Because of the use of "companion" controllers, devices connected to ports on USB 2.0 root hubs (EHCI host controllers) will get one path ID if they are high speed, and a different one if they are full or low speed. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 USB_MAKE_PATH(9)

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hubd(7D)																  hubd(7D)

hubd - USB hub driver SYNOPSIS
hub@unit-address The hubd is a USBA (Solaris USB Architecture) compliant client driver that supports USB hubs conforming to the Universal Serial Bus Speci- fication 2.0. The hubd driver supports bus-powered and self-powered hubs. The driver supports hubs with individual port power, ganged power and no power switching. When a device is attached to a hub port, the hubd driver enumerates the device by determining its type and assigning an address to it. For multi-configuration devices, hubd sets the preferred configuration (refer to cfgadm_usb(1M) to select a configuration). The hubd driver attaches a driver to the device if one is available for the default or selected configuration. When the device is disconnected from the hub port, the hubd driver offlines any driver instance attached to the device. /kernel/drv/hubd 32- bit ELF kernel module /kernel/drv/amd64/hubd 64- bit ELF kernel module /kernel/drv/sparcv9/hubd 64-bit SPARC ELF kernel module See attributes(5) for a description of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Architecture |SPARC, , PCI-based systems | +-----------------------------+-----------------------------+ |Availability |SUNWusb | +-----------------------------+-----------------------------+ cfgadm_usb(1M), attributes(5), usba(7D) Writing Device Drivers Universal Serial Bus Specification 2.0 System Administration Guide: Basic Administration http://www.sun.com/io In addition to being logged, the following messages may also appear on the system console. Messages are formatted in the following manner: WARNING: <device path> <hubd<instance number>): Message... where <instance number> is the instance number of hubd and <device path> is the physical path to the device in /devices directory. Messages from the root hub are displayed with a usb<instance number> prefix instead of hub<instance number> as the root hub is an integrated part of the host controller. Connecting device on port <number> failed. The driver failed to enumerate the device connected on port <number> of hub. If enumeration fails, disconnect and re-connect. Use of a USB 1.0 hub behind a high speed port may cause unexpected failures. Devices connected to a USB 1.0 hub which are in turn connected to an external USB 2.0 hub, may misbehave unexpectedly or suddenly go offline. This is due to a documented incompatibility between USB 1.0 hubs and USB 2.0 hub Transaction Translators. Please use only USB 2.0 or USB 1.1 hubs behind high-speed ports. Connecting a high speed device to a non-high speed hub (port x) will result in a loss of performance. Please connect the device to a high speed port to get the maximum performance. USB 2.0 devices connected to USB 1.0 or 1.1 hubs cannot run at their highest speed, even when the hub is in turn connected to a high- speed port. For best performance, reconnect without going through a USB 1.0 or 1.1 hub. Cannot access <device>. Please reconnect. This hub has been disconnected because a device other than the original one has been inserted. The driver informs you of this fact by displaying the name of the original device. Devices not identical to the previous one on this port. Please disconnect and reconnect. Same condition as described above; however in this case, the driver is unable to identify the original device with a name string. Hub driver supports max of <n> ports on hub. Hence, using the first <number of physical ports> of <n> ports available. The current hub driver supports hubs that have <n> ports or less. A hub with more than <n> ports has been plugged in. Only the first <n> out of the total <number of physical ports> ports are usable. The following messages may be logged into the system log. They are formatted in the following manner: <device path> <hubd<instance number>): message... Global over current condition, please disconnect hub. The driver detected an over current condition. This means that the aggregate current being drawn by the devices on the downstream port exceeds a preset value. Refer to section and 11.13 of the Universal Serial Bus Specification 2.0. You must remove and insert this hub to render it and its downstream devices functional again. If this message continues to display for a particular hub, you may need to remove downstream devices to eliminate the problem. Local power has been lost, please disconnect hub. A USB self-powered hub has lost external power. All USB devices connected down-stream from this hub will cease to function. Disconnect the hub, plug in the external power-supply and then plug in the hub again. Local power has been lost, the hub could draw <x> mA power from the USB bus. A USB self/bus-powered hub has lost external power. Some USB devices connected down-stream from this hub may cease to func- tion. Disconnect the external power-supply and then plug in the hub again. 20 June 2005 hubd(7D)
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