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Imx6ull Overlay Framebuffer with Alpha Blending

Question asked by Henri Koch on Dec 11, 2019
Latest reply on Dec 15, 2019 by karan gajjar



I am trying to enable the alpha blending capability as stated in the imx6ull reference manual to perform overlay on the main framebuffer. As so, I have my framebuffer buffer fb0 correctly set to ARGB32 format inside the mxsfb.c driver for a display (320x240x32) sending data over a 8 bits bus-width interface.


I configured the alpha blending hardware register to my need (set correct format to argb32, alpha_ctrl to embedded, ... ) and the framebuffer fb1 initialized is also in the correct format and size (320x240x32).


I understood that I need to unblank the fb1 framebuffer to activate the overlay but insteed of running properly, the screen starts to indicate random black and white line before the whole system stop working.


I also checked the register configuration using the memtool and everything seems to be fine. The same is happening if activate the AS_ENABLE register directly from this tool.


  1. Any thought about the problem that I am facing ?
  2. Is the ELCDIF AS register independent from PXP register ? I am not using the PXP right know.


Thank you !