[1/3] RFT: drm/pl111: Support grayscale

[David Lechner]

On 7/23/19 8:37 AM, Linus Walleij wrote:
> Migrating the TI nspire calculators to use the PL111 driver for
> framebuffer requires grayscale support for the elder panel
> which uses 8bit grayscale only.
> 
> DRM does not support 8bit grayscale framebuffers in memory,
> but by defining the bus format to be MEDIA_BUS_FMT_Y8_1X8 we
> can get the hardware to turn on a grayscaling feature and
> convert the RGB framebuffer to grayscale for us.
> 


What would it take to add proper grayscale framebuffer
support to DRM? I've been using the RGB to gray conversion
method for a while now with st7586 and it is OK but is
creates extra work if you want things to actually look
"good" instead of "OK" because you have to add code to
userspace programs to craft images in a certain way so
that they come out on the other side looking as intended
on the actual display.