drm/edid: parse YCBCR420 videomodes from EDID

drm/edid: parse YCBCR420 videomodes from EDID

HDMI 2.0 spec adds support for YCBCR420 sub-sampled output.
CEA-861-F adds two new blocks in EDID's CEA extension blocks,
to provide information about sink's YCBCR420 output capabilities.

These blocks are:

- YCBCR420vdb(YCBCR 420 video data block):
This block contains VICs of video modes, which can be sopported only
in YCBCR420 output mode (Not in RGB/YCBCR444/422. Its like a normal
SVD block, valid for YCBCR420 modes only.

- YCBCR420cmdb(YCBCR 420 capability map data block):
This block gives information about video modes which can support
YCBCR420 output mode also (along with RGB,YCBCR444/422 etc) This
block contains a bitmap index of normal svd videomodes, which can
support YCBCR420 output too.
So if bit 0 from first vcb byte is set, first video mode in the svd
list can support YCBCR420 output too. Bit 1 means second video mode
from svd list can support YCBCR420 output too, and so on.

This patch adds two bitmaps in display's hdmi_info structure, one each
for VCB and VDB modes. If the source is HDMI 2.0 capable, this patch
adds:
- VDB modes (YCBCR 420 only modes) in connector's mode list, also makes
  an entry in the vdb_bitmap per vic.
- VCB modes (YCBCR 420 also modes) only entry in the vcb_bitmap.

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Jose Abreu <joabreu@synopsys.com>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
V2: Addressed
    Review comments from Emil:
    - Use 1ULL<<i instead of 1<<i to make sure the output is 64bit.
    - Use the suggested method for updating dbmap.
    - Add documentation for YCBCR420_vcb_map to fix kbuild warning.

    Review comments from Ville:
    - Do not expose the YCBCR420 flags in uabi layer, keep it internal.
    - Save a map of YCBCR420 modes for future reference.
    - Check db length before trying to parse extended tag.
    - Add a warning if there are > 64 modes in capability map block.
    - Use y420cmdb in function names and macros while dealing with vcb
      to be aligned with spec.
    - Move the display information parsing block ahead of mode parsing
      blocks.

V3: Addressed design/review comments from Ville
    - Do not add flags in video modes, else we have to expose them to user
    - There should not be a UABI change, and kernel should detect the
      choice of the output based on type of mode, and the bitmaps.
    - Use standard bitops from kernel bitmap header, instead of calculating
      bit positions manually.

V4: Addressed review comments from Ville:
    - s/ycbcr_420_vdb/y420vdb
    - s/ycbcr_420_vcb/y420cmdb
    - Be less verbose on description of do_y420vdb_modes
    - Move newmode variable in the loop scope.
    - Use svd_to_vic() to get a VIC, instead of 0x7f
    - Remove bitmap description for CMDB modes & VDB modes
    - Dont add connector->ycbcr_420_allowed check for cmdb modes
    - Remove 'len' variable, in is_y420cmdb function, which is used
      only once
    - Add length check in is_y420vdb function
    - Remove unnecessary if (!db) check in function parse_y420cmdb_bitmap
    - Do not add print about YCBCR 420 modes
    - Fix indentation in few places
    - Move ycbcr420_dc_modes in next patch, where its used
    - Add a separate patch for movement of drm_add_display_info()

V5: Addressed review comments from Ville:
    - Add the patch which cleans up the current EXTENDED_TAG usage
    - Make y420_cmdb_map u64
    - Do not block ycbcr420 modes while parsing the EDID, rather
      add a separate helper function to prune ycbcr420-only modes from
      connector's probed modes.

V6: Rebase
V7: Move this patch after the 420_only validation patch (Ville)
V8: Addressed review comments from Ville
    - use cea_vic_valid check before adding cmdb/vdb modes
    - add check for i < 64 while adding cmdb modes
    - use 1ULL while checking bitmap

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1500028426-14883-1-git-send-email-shashank.sharma@intel.com
[vsyrjala: Fix checkpatch complaints and indentation]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>