Ankit Nautiyal authored Mar 19, 2097 and Pekka Paalanen committed Jul 06, 2018

The flag bits 19-22 of the connector modes, provide the aspect-ratio
information. This information can be stored in flags bits of the
weston mode structure, so that it can used for setting a mode with a
particular aspect-ratio.
Currently, DRM layer supports aspect-ratio with atomic-modesetting by
default. For legacy modeset path, the user-space needs to set the
drm client cap for aspect-ratio, if it wants aspect-ratio information
in modes.

This patch:
- preserves aspect-ratio flags from kernel video modes and
  accommodates it in wayland mode.
- uses aspect-ratio to pick the appropriate mode during modeset.
- changes the mode format in configuration file weston.ini to
  accommodate aspect-ratio information as:
  WIDTHxHEIGHT@REFRESH-RATE ASPECT-RATIO
  The aspect-ratio can take the following values :
  4:3, 16:9, 64:27, 256:135.

v2: As per recommendation from Pekka Paalanen, Quentin Glidic,
Daniel Stone, dropped the aspect-ratio info from wayland protocol,
thereby avoiding exposure of aspect-ratio to the client.

v3: As suggested by Pekka Paalanen, added aspect_ratio field to store
aspect-ratio information from the drm. Also added drm client
capability for aspect-ratio, as recommended by Daniel Vetter.

v4: Minor modifications and fixes as suggested by Pekka Paalanen.

v5: Rebased, fixed some styling issues, and added aspect-ratio
information while printing weston_modes.

v6: Moved the man pages changes to a different patch. Minor
reorganization of code as suggested by Pekka Paalanen.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
[Pekka: replace ARRAY_SIZE with ARRAY_LENGTH]
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>