RGB24 LCD - can't change the polarity of the DE signal?

[Rasmus Backman]

Hello,

I'm trying to add a E50RG84885LWAM520-CA TFT LCD to my BeagleBone Black Wireless. It has an ILI9806E controller IC.

I can't seem to get the correct polarity for the DE signal. The controller is expecting an active LOW DE signal.

I have tried setting de-active = <0>; to my devicetree overlay, but it seems that setting is ignored. When I measure what the output of the BBBW is, all other control signals look correct except for that one.

My overlay is enabled in /boot/uEnv.txt: 

dtb_overlay=/lib/firmware/RB-TFT-PROTOTYPE-V1-00A1.dtbo

Apart from measuring the output, I can also see with fbset that the resolution and bpp settings have been accepted, so the .dtbo is definately loaded at boot...

My whole devicetree file is here: https://gist.github.com/RasmusB/cea0cb4c2f69259497b3e37ac0347e76

Any ideas on where I should look next?