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.TH "USB_GET_DEVICE_DESCRIPTOR" "9" "17 July 2003" "" ""

.SH NAME
usb_get_device_descriptor \- (re)reads the device descriptor
.SH SYNOPSIS
.sp
\fB
.sp
int usb_get_device_descriptor  (struct usb_device * \fIdev\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIdev\fB\fR
the device whose device descriptor is being updated
.SH "CONTEXT"
.PP
!in_interrupt ()
.SH "DESCRIPTION"
.PP
Updates the copy of the device descriptor stored in the device structure,
which dedicates space for this purpose.  Note that several fields are
converted to the host CPU's byte order:  the USB version (bcdUSB), and
vendors product and version fields (idVendor, idProduct, and bcdDevice).
That lets device drivers compare against non-byteswapped constants.
.PP
There's normally no need to use this call, although some devices
will change their descriptors after events like updating firmware.
.PP
This call is synchronous, and may not be used in an interrupt context.
.PP
Returns the number of bytes received on success, or else the status code
returned by the underlying \fBusb_control_msg\fR call.
.SH "ABOUT THIS DOCUMENT"
.PP
This documentation is free software; you can redistribute
it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later
version.
.PP
This program is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
.PP
You should have received a copy of the GNU General Public
License along with this program; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA
.PP
For more details see the file COPYING in the source
distribution of Linux.
.PP
If you have comments on the formatting of this manpage, then please contact
Michael Still (mikal@stillhq.com).
.PP
This documentation was generated with kernel version 2.5.71.