diff options
Diffstat (limited to 'Documentation/usb/proc_usb_info.txt')
| -rw-r--r-- | Documentation/usb/proc_usb_info.txt | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/Documentation/usb/proc_usb_info.txt b/Documentation/usb/proc_usb_info.txt index afe596d5f20..98be9198267 100644 --- a/Documentation/usb/proc_usb_info.txt +++ b/Documentation/usb/proc_usb_info.txt @@ -7,7 +7,7 @@ The usbfs filesystem for USB devices is traditionally mounted at /proc/bus/usb. It provides the /proc/bus/usb/devices file, as well as the /proc/bus/usb/BBB/DDD files. -In many modern systems the usbfs filsystem isn't used at all. Instead +In many modern systems the usbfs filesystem isn't used at all. Instead USB device nodes are created under /dev/usb/ or someplace similar. The "devices" file is available in debugfs, typically as /sys/kernel/debug/usb/devices. @@ -54,9 +54,12 @@ it and 002/048 sometime later. These files can be read as binary data. The binary data consists of first the device descriptor, then the descriptors for each -configuration of the device. Multi-byte fields in the device and -configuration descriptors, but not other descriptors, are converted -to host endianness by the kernel. This information is also shown +configuration of the device. Multi-byte fields in the device descriptor +are converted to host endianness by the kernel. The configuration +descriptors are in bus endian format! The configuration descriptor +are wTotalLength bytes apart. If a device returns less configuration +descriptor data than indicated by wTotalLength there will be a hole in +the file for the missing bytes. This information is also shown in text form by the /proc/bus/usb/devices file, described later. These files may also be used to write user-level drivers for the USB |