How to specify panel bit order in driver?

[John Watts]

Hello there,

A while ago I added support for the FS035VG158 panel to the kernel, with its
use case being on a Allwinner T113 board.

While troubleshooting some other issue (I will be posting about that this
weekend) I found that I need to tell the panel controller to use a bit depth of
18-bit in order for the panel to work correctly.

I plan to add another panel to the kernel that also requires setting the bit
depth, but has more configurations than just 24, 18, 16, it also supports
packing 18 of the bits together.

How all of this is configured depends on how the board and panel are wired
together, it can't be determined at runtime based on pixel formats or anything
like that. It seems to me that this needs to be specified in the device tree.

My question is: How would I represent this? A property like 'bit-depth'?
'color-mapping'? Or is there already some subsystem or convention designed for
this?

John.