DCD Table (Device Configuration Data Table) in i.MX

Some technical notes: The i.MX SoCs USB ROM boot mode supports doing register writesand file uploads. The files are usually uploaded to SDRAM. For this to work the SDRAM has to be initialized first. The information necessary to do this is contained in the imximage itself, more exactly in the DCD table. The imx-usb-loader parses this table and translates the DCD into register writes, basically it resembles what the i.MX would do in ROM code when the same image would be loaded from another bootsource like SD/MMC cards. Still the i.MX needs the DCD table to be uploaded. The i.MX would execute the DCD data again, which would result in corrupting the just configured SDRAM. The imx-usb-loader prevents this by setting the DCD length to 0x0 before uploading the image.
The i.MX Boot ROM supports different types of images to upload. The imx-usb-loader currently only handles the simple case of uploading a single image which is executed right after downloading.