Pekka Paalanen authored Jul 08, 2021 and Pekka Paalanen committed May 02, 2022

This is the switch to turn HDR mode on.

The values in the enumeration come straight from CTA-861-G standard.
Monitors advertise support for some of the HDR modes in their EDID, and
I am not aware of any other way to detect if a HDR mode actually works
or not. Different monitors may support different and multiple modes.
Different modes may look different. Therefore the high-level choice of
how to drive a HDR video sink is left for the Weston frontend to decide.

All the details like what HDR metadata to use are left for the color
manager.

This commit adds the libweston API for backends to advertise support and
for frontends to choose a mode. Backend and frontend implementations
follow in other commits.

The frontend API does not limit the EOTF mode to the supported ones to
allow experimentation and overriding EDID.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>