u-boot/doc/README.sdp

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2 SDP in U-Boot
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5 SDP stands for serial download protocol. It is the protocol used in NXP's
7 image to the chip over USB and UART serial connection.
9 The implementation in U-Boot uses the USB Downloader Gadget (g_dnl) to
10 provide a SDP implementation over USB. This allows to download program
11 images to the target in SPL/U-Boot using the same protocol/tooling the
14 The SDP protocol over USB is a USB HID class protocol. USB HID class
15 protocols allow to access a USB device without OS specific drivers. The
16 U-Boot implementation has primarly been tested using the open source
21 for imx_loader's imx_usb utility which allow to interpret the U-Boot
22 specific legacy image format (see mkimage(1)). Also the U-Boot side
23 support beside the i.MX specific header the U-Boot legacy header.
26 -----
28 This implementation can be started in U-Boot using the sdp command
32 A typical use case is downloading full U-Boot after SPL has been
34 detection the SPL will run the SDP implementation automatically in
41   Trying to boot from USB SDP
42   SDP: initialize...
43   SDP: handle requests...
46 the boot ROM's SDP protocol. The USB VID/PID will depend on standard
47 U-Boot configurations CONFIG_G_DNL_(VENDOR|PRODUCT)_NUM. Make sure
48 imx_usb is aware of the USB VID/PID for your device by adding a
58 This allows to download the regular U-Boot with legacy image headers
59 (u-boot.img) using a second invocation of imx_usb:
61   # imx_usb u-boot.img
63 Furthermore, when U-Boot is running the sdp command can be used to
95   u-boot.img:jump header2
97 With that SPL and U-Boot can be downloaded with a single invocation