'\" t
.\"     Title: usb_gadget_config_buf
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: June 2017
.\"    Manual: Kernel Mode Gadget API
.\"    Source: Kernel Hackers Manual 4.11.3
.\"  Language: English
.\"
.TH "USB_GADGET_CONFIG_BU" "9" "June 2017" "Kernel Hackers Manual 4\&.11\&" "Kernel Mode Gadget API"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
usb_gadget_config_buf \- builts a complete configuration descriptor
.SH "SYNOPSIS"
.HP \w'int\ usb_gadget_config_buf('u
.BI "int usb_gadget_config_buf(const\ struct\ usb_config_descriptor\ *\ " "config" ", void\ *\ " "buf" ", unsigned\ " "length" ", const\ struct\ usb_descriptor_header\ **\ " "desc" ");"
.SH "ARGUMENTS"
.PP
\fIconst struct usb_config_descriptor * config\fR
.RS 4
Header for the descriptor, including characteristics such as power requirements and number of interfaces\&.
.RE
.PP
\fIvoid * buf\fR
.RS 4
Buffer for the resulting configuration descriptor\&.
.RE
.PP
\fIunsigned length\fR
.RS 4
Length of buffer\&. If this is not big enough to hold the entire configuration descriptor, an error code will be returned\&.
.RE
.PP
\fIconst struct usb_descriptor_header ** desc\fR
.RS 4
Null\-terminated vector of pointers to the descriptors (interface, endpoint, etc) defining all functions in this device configuration\&.
.RE
.SH "DESCRIPTION"
.PP
This copies descriptors into the response buffer, building a descriptor for that configuration\&. It returns the buffer length or a negative status code\&. The config\&.wTotalLength field is set to match the length of the result, but other descriptor fields (including power usage and interface count) must be set by the caller\&.
.PP
Gadget drivers could use this when constructing a config descriptor in response to USB_REQ_GET_DESCRIPTOR\&. They will need to patch the resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed\&.
.SH "AUTHOR"
.PP
\fBDavid Brownell\fR <\&dbrownell@users.sourceforge.net\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br