For some reason xe and i915 each have an identical (fortunately)
copy of intel_fbdev_fb.h. The xe copy actually only gets included
by xe's intel_fbdev_fb.c, and the i915 copy by everyone else,
include intel_fbdev.c which is the actual caller of the
functions declared in the header.

This means the xe and i915 headers are free to define/declare
completely incompatible things and the build would still succeed
as long as the symbol names match.

That is not a good thing, so let's nuke xe's copy of the header
so that everyone will use the same header, and be forced to
agree on the same API/ABI.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240506183331.7720-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>

As for display, the intent is to share the display code with the i915
driver so that there is maximum reuse there.

We do this by recompiling i915/display code twice.
Now that i915 has been adapted to support the Xe build, we can add
the xe/display support.

This initial work is a collaboration of many people and unfortunately
this squashed patch won't fully honor the proper credits.
But let's try to add a few from the squashed patches:

Co-developed-by: Matthew Brost <matthew.brost@intel.com>
Co-developed-by: Jani Nikula <jani.nikula@intel.com>
Co-developed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Co-developed-by: Matt Roper <matthew.d.roper@intel.com>
Co-developed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Co-developed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Co-developed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>