[Intel-gfx] AVI infoframes: default aspect ratio/VIC for CEA modes

[Gohad, Tushar]

Folks,

A newbie question - When filling in an HDMI AVI infoframe, how does one correctly determine the "default" picture aspect ratio (and VIC) for CEA modes that support multiple (4:3 and 16:9) aspect ratios.  720x576p for example, corresponds to VIC 17 or 18:

        /* 17 - 720x576 at 50Hz */
        { DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 27000, 720, 732,
                   796, 864, 0, 576, 581, 586, 625, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),
          .vrefresh = 50, },
        /* 18 - 720x576 at 50Hz */
        { DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 27000, 720, 732,
                   796, 864, 0, 576, 581, 586, 625, 0,
                   DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),
          .vrefresh = 50, },

Should the "picture aspect ratio" information be derived from sink EDID (from detailed/cvt/standard timings)? .. possibly in drm_add_edid_modes() and store the picture aspect ratio in drm_display_mode perhaps, for later use?  Trying to get a better understanding of how this usually works.

As an aside, to match VIC correctly, shouldn't drm_match_cea_mode() take into account picture aspect ratio as well?

Cheers,
Tushar