i.MX8MM USB Serial Download Support (Booting via imx-usb-loader, uuu, etc.)
There are multiple issues with USB OTG and SDP support in U-Boot for our Kontron i.MX8MM boards:
- Changes to U-Boot for enabling support got rejected because of missing devicetree/DM implementation. Until now, nobody came up with a proper solution.
- When enabling USB and SDP support in SPL (with the above patches applied) we hit the SPL binary size constraint as we also have MTD and other stuff enabled that bloats the SPL. We currently don't have a solution for this.
Ideas for possible workarounds:
- Use a stripped U-Boot configuration that disables MTD and/or other stuff to make space for the USB/SDP code, when working with the serial download feature during development. You can put this on an SD card and remove it after finishing to fall back to the fully featured bootloader on the flash.
- Disable MTD support in U-Boot SPL and boot directly from eMMC instead of SPI NOR
- Try to reduce the SPL size by using
CONFIG_LTO
and/or other measures
Edited by Frieder Schrempf