[PATCH RFC 0/5] drm/meson: Add support for HDMI2.0 YUV420 4k60

[Neil Armstrong]

The Synopsys DW-HDMI CSC does not support downsampling to YUV420, so
the encoder must downsamle before, feeding the controller with a YUV420
pixel stream.

The encoder must declare the new bus format enc encoding the bridge, in
order to take it in account.

To solve this, a new format_set() bridge op is added, permitting setting
a new input bus format and encoding to the bridge chain.

This solves YUV420 setup, but also solved setting 10bit, 12bit or 16bit
input bus format in order to support HDMI >8bit depths.

The DW-HDMI controller is updated to dynamically select a coherent output
bus format depending on the input bus format and on the internal CSC
supported modes.

The DW-HDMI is also updated to support the connector display_info bus_formats
entry to permit forcing a specific output bus format to force, for example,
an YUV444 output format instead of the default RGB output bus format.

Only the meson DRM dw_hdmi glue allows ycbcr420 modes, so no breakage
is expected here.

The remaining patches adds support for 4:2:0 output and clock setup for
the meson DW-HDMI glue, and how YUV444 output can be forced.

Neil Armstrong (5):
  drm/bridge: dw-hdmi: allow ycbcr420 modes for >= 0x200a
  drm/bridge: add encoder support to specify bridge input format
  drm/bridge: dw-hdmi: Add support for dynamic output format setup
  drm/meson: Add YUV420 output support
  drm/meson: Output in YUV444 if sink supports it

 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 127 ++++++++++++++++++++--
 drivers/gpu/drm/drm_bridge.c              |  35 ++++++
 drivers/gpu/drm/meson/meson_dw_hdmi.c     | 111 ++++++++++++++++---
 drivers/gpu/drm/meson/meson_vclk.c        |  93 ++++++++++++----
 drivers/gpu/drm/meson/meson_vclk.h        |   7 +-
 drivers/gpu/drm/meson/meson_venc.c        |   6 +-
 drivers/gpu/drm/meson/meson_venc.h        |  11 ++
 drivers/gpu/drm/meson/meson_venc_cvbs.c   |   3 +-
 include/drm/bridge/dw_hdmi.h              |   1 +
 include/drm/drm_bridge.h                  |  19 ++++
 10 files changed, 358 insertions(+), 55 deletions(-)

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2.21.0