# DFU

## Introduction

Device Firmware Update is a standard that allows USB devices to be easily and
safely updated by any operating system.

## Firmware Format

The daemon will decompress the cabinet archive and extract a firmware blob in
DFU or DfuSe file format.

This plugin supports the following protocol IDs:

* org.usb.dfu
* com.st.dfuse

## GUID Generation

These devices use the standard USB DeviceInstanceId values, e.g.

* `USB\VID_273F&PID_1003&REV_0001`
* `USB\VID_273F&PID_1003`
* `USB\VID_273F`

## Update Behavior

A DFU device usually presents in runtime mode (with optional DFU runtime), but
on detach re-enumerates with an additional required DFU descriptor. On attach
the device again re-enumerates back to the runtime mode.

For this reason the `REPLUG_MATCH_GUID` internal device flag is used so that
the bootloader and runtime modes are treated as the same device.

## Vendor ID Security

The vendor ID is set from the USB vendor, for example `USB:0x0A12`

## Quirk Use

This plugin uses the following plugin-specific quirks:

### DfuFlags

Optional quirks for a DFU device which doesn't follow the DFU 1.0 or 1.1 specification.

Since: 1.0.1

### DfuForceVersion

Forces a specific DFU version for the hardware device. This is required if the device does not set, or sets incorrectly, items in the DFU functional descriptor.

Since: 1.0.1

### DfuForceTimeout

Forces a specific device timeout, in ms.

Since: 1.4.0

### DfuForceTransferSize

Forces a target transfer size, in bytes.

Since: 1.5.6

## External Interface Access

This plugin requires read/write access to `/dev/bus/usb`.