diff options
Diffstat (limited to 'src/tegrarcm.1.in')
| -rw-r--r-- | src/tegrarcm.1.in | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/tegrarcm.1.in b/src/tegrarcm.1.in index f747fd8..f8009b9 100644 --- a/src/tegrarcm.1.in +++ b/src/tegrarcm.1.in @@ -79,6 +79,80 @@ built-in one. .TP .B \-\-miniloader_entry \fImlentry\fP Specify the entry address of the miniloader. +.TP +.B \-\-usb\-port\-path \fIpath\fP +Specify the physical USB port path of the Tegra device to control. + +.SH USB PORT PATH + +By default, tegrarcm operates on the first USB applicable device it finds. +In a system that contains multiple Tegra devices, the user may wish to +specify which device tegrarcm should operate upon. The \-\-usb\-port\-path +option allows this, and in a manner that is most immune to the set of attached +USB devices varying. + +Note that the USB port path is associated with a physical USB port on a +particular hub. This value will vary if you physically re-organize your USB +connections. This feature is still useful even if your USB topology changes, +providing you have some other mechanism to differentiate attached devices. For +example, you could use a wrapper script around tegrarcm that identifies the +appropriate device by other means, then automatically calculates the USB port +path using the procedures below, and passes the value to tegrarcm. + +To determine the USB port path of a device, you must plug it in and find the +current USB bus and USB device number of the device, then map that to the USB +port path. Simply run lsusb to find the current USB bus and device number. If +you have multiple NVIDIA devices attached, you may need to unplug and replug +the Tegra device to ensure you know which is which (all while not changing the +state of any other USB devices so you don't confuse yourself). + +.nf +$ lsusb +... +Bus 003 Device 039: ID 0955:7721 NVidia Corp. +Bus 003 Device 045: ID 0955:7140 NVidia Corp. +... +fi + +Then, to determine the USB port path, do one of: + +.IP 1. + +Execute udevmadm on the USB device, and look for the DEVPATH entry. The +final component in the path is the USB port path: + +.nf +$ udevadm info /dev/bus/usb/003/045 +P: /devices/pci0000:00/0000:00:14.0/usb3/3-10/3-10.4 +N: bus/usb/003/045 +E: BUSNUM=003 +E: DEVNUM=045 +E: DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-10/3-10.4 +.fi + +.IP 2. + +Look at all the sub-directories of /sys/bus/usb/devices/* that do not +contain either ":" or "usb". Each of these will contain a busnum and +devnum file. Find the directory which matches the lsusb output, and use +its name: + +.nf +$ cat /sys/bus/usb/devices/3-10.4/busnum +3 +$ cat /sys/bus/usb/devices/3-10.4/devnum +45 +.fi + +Alternatively, you may already have udev rules that create a device node +symlink for the device (after some specific identification algorithm). In +that case, you can search the udev output for MAJOR/MINOR values, or +/sys/bus/usb/devices/* directories for "dev" files, that match the device +node the symlink points to. + +Once the port path is known, this value will not vary unless your USB +connections are physically changed, so you can use it over and over +without repeating the steps above. .SH EXAMPLES To download u-boot firmware to a Tegra20 seaboard: |