Support for jeida-18 in panel-lvds for i.MX8MP

[DiegoFSL]

Hi,

we have an AVNET MSC SM2S IMX8MPLUS SOM:
https://embedded.avnet.com/product/msc-sm2s-imx8plus/

We have to support a Densitron JEIDA 18-bit LVDS panel (6 bit per color) connected to this SOM through the carrier board.

The AVNET kernel provides several example device tree overlays to support jeida-24 or vesa-24 bit LVDS panel, but no example for 18-bit LVDS panel.

In particular, while we can drive our Densitron 18-bit LVDS panel with jeida-24, as the 2 LSB for each color are in the fourth unused LVDS lane, if we try to use jeida-18 we get the following error:

imx-lcdifv3 32e90000.lcd-controller: unknown bus format: 0x1009

This error is reported both in kernel 5.10.35 and 5.15.52 whenever we try to switch from jeida-24 to jeida-18. The kernel logo appears with incorrect colors if jeida-18 is used.

Has anybody tested jeida-18 data-mapping for LVDS panels with i.MX8M Plus SOC?

Thanks in advance

[DiegoFSL]

To clarify, the underlying issue is that we have color banding due to the 18-bit colors supported by the display.

A suspect is that using a jeida-24 format for the display may let the Qt framework (Boot to Qt) think that the display is 24-bit and so dithering is not needed. See our post in the Qt forum:
https://forum.qt.io/topic/150200/qt-eglfs-dithering-for-18-bit-color-display

Thanks