[PATCH v9 00/10] drm: add DRM HDMI Codec framework

[Dmitry Baryshkov]

While porting lt9611 DSI-to-HDMI bridge driver to use HDMI Connector
framework, I stumbled upon an issue while handling the Audio InfoFrames.
The HDMI codec callbacks weren't receiving the drm_atomic_state, so
there was no simple way to get the drm_connector that stayed at the end
of the bridge chain. At the same point the drm_hdmi_connector functions
expected to get drm_connector instance.

While looking for a way to solve the issue, I stumbled upon several
deficiencies in existing hdmi_codec_ops implementations. Only few of the
implementations were able to handle codec's 'plugged' callback. One
third of the drivers didn't implement the get_eld() callback.

Most of the issues can be solved if drm_connector handles
hdmi-audio-codec on its own, delegating functionality to the actual
implementation, be it a driver that implements drm_connector or
drm_bridge.

Implement such high-level framework, adding proper support for Audio
InfoFrame generation to the LT9611 driver.

Several design decisions to be kept in mind:

- drm_connector_hdmi_codec is kept as simple as possible. It implements
  generic functionality (ELD, hotplug, registration).

- drm_hdmi_connector sets up HDMI codec device if the connector
  is setup correspondingly (either I2S or S/PDIF is marked as
  supported).

- drm_bridge_connector provides a way to link HDMI audio codec
  funcionality in the drm_bridge with the drm_connector_hdmi_codec
  framework.

- It might be worth reverting the no_i2s_capture / no_spdif_capture
  bits. Only TDA889x driver sets them, while it's safe to assume that
  most of HDMI / DP devices do not support ARC / capture. I think the
  drivers should opt-in capture support rather than having to opt-out of
  it.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
Changes in v9:
- Fix a part of the hdmi_audio rename sneaking into the
  drm_bridge_connector patch.
- Move HDMI Audio implementation into drm_display_helper so that it
  doesn't get compiled for driver which do not require it.
- Link to v8: https://lore.kernel.org/r/20241220-drm-bridge-hdmi-connector-v8-0-2399dbae2990@xxxxxxxxxx

Changes in v8:
- Mass rename hdmi_codec -> hdmi_audio, drop redundant audio_ prefixes
  from several callbacks (Maxime)
- Fix the commit message to stop mentioning
  drm_atomic_helper_connector_hdmi_update_edid() (Maxime)
- Link to v7: https://lore.kernel.org/r/20241217-drm-bridge-hdmi-connector-v7-0-cb9df2b6a515@xxxxxxxxxx

Changes in v7:
- Renamed drm_connector_hdmi_codec_init() to
  drm_connector_hdmi_audio_init() (Maxime)
- Added extra empty line in struct drm_connector_hdmi_codec_funcs
  (Maxime)
- Dropped if/else from drm_bridge_connector_audio_startup() (Maxime)
- Added optional .read_edid() callback and reworked
  drm_atomic_helper_connector_hdmi_hotplug() to use that callback
  instead of having an internal function which accepts EDID (Maxime)
- Made VC4 and drm_bridge_connector use .force() in addition to
  .detect() and .detect_ctx().
- Moved HDMI codec functions out of struct drm_connector_hdmi_funcs.
  Assign them from drm_connector_hdmi_audio_init().
- Documented struct drm_connector_hdmi_codec and its fields.
- Link to v6: https://lore.kernel.org/r/20241206-drm-bridge-hdmi-connector-v6-0-50dc145a9c06@xxxxxxxxxx

Changes in v6:
- Dropped extra checks on the EDID (Jani)
- Reworked drmm_connector_hdmi_init(), splitting the codec init to a
  separate optional function rather than passing arguments through
  drm_connector (Maxime)
- Reworked EDID update functions (Maxime, Jani)
- No longer refresh the EDID in vc4_hdmi_connector_get_modes(), it is
  redundant as vc4_hdmi_connector_detect_cxtx() already does that.
- Link to v5: https://lore.kernel.org/r/20241201-drm-bridge-hdmi-connector-v5-0-b5316e82f61a@xxxxxxxxxx

Changes in v5:
- Moved prototypes from drm_internal.h to
  drm_connector_hdmi_codec_internal.h (Jani)
- Rebased on top of ELD mutex series, resolving the long-standing FIXME
- Converted the VC4 driver (compile-tested only)
- Link to v4: https://lore.kernel.org/r/20241122-drm-bridge-hdmi-connector-v4-0-b4d69d6e3bd9@xxxxxxxxxx

Changes in v4:
- Added forward declaration of struct drm_edid (LKP)
- Fixed kerneldoc for drm_atomic_helper_connector_hdmi_update_edid().
- Link to v3: https://lore.kernel.org/r/20241109-drm-bridge-hdmi-connector-v3-0-c15afdca5884@xxxxxxxxxx

Changes in v3:
- Dropped RFC status
- Fixed drm_connector_hdmi_codec_init() kerneldoc (LKP)
- Dropped double underscore prefix from
  __drm_atomic_helper_connector_hdmi_update_edid() (Jani)
- Moved drm_edid_free() from
  drm_atomic_helper_connector_hdmi_update_edid() to the caller's side
  (Jani)
- Link to v2: https://lore.kernel.org/r/20241101-drm-bridge-hdmi-connector-v2-0-739ef9addf9e@xxxxxxxxxx

Changes in v2:
- Use drm_atomic_get_old_connector_for_encoder in atomic_disable() to
  prevent it from crashing
- Reworked HDMI codec init/exit, removing drmm_ calls (Maxime)
- Drafted the helper to be called from .detect_ctx() that performs HDMI
  Connector maintenance duties (Maxime)
- Moved no_capture_mute to struct hdmi_codec_pdata
- Link to v1: https://lore.kernel.org/r/20240615-drm-bridge-hdmi-connector-v1-0-d59fc7865ab2@xxxxxxxxxx

---
Dmitry Baryshkov (10):
      ASoC: hdmi-codec: pass data to get_dai_id too
      ASoC: hdmi-codec: move no_capture_mute to struct hdmi_codec_pdata
      drm/connector: implement generic HDMI audio helpers
      drm/bridge: connector: add support for HDMI codec framework
      drm/bridge: lt9611: switch to using the DRM HDMI codec framework
      drm/display/hdmi: implement hotplug functions
      drm/bridge_connector: hook drm_atomic_helper_connector_hdmi_hotplug()
      drm/vc4: hdmi: switch to using generic HDMI Codec infrastructure
      drm/vc4: hdmi: stop rereading EDID in get_modes()
      drm/vc4: hdmi: use drm_atomic_helper_connector_hdmi_hotplug()

 drivers/gpu/drm/bridge/adv7511/adv7511_audio.c     |   3 +-
 drivers/gpu/drm/bridge/analogix/anx7625.c          |   3 +-
 drivers/gpu/drm/bridge/ite-it66121.c               |   2 +-
 drivers/gpu/drm/bridge/lontium-lt9611.c            | 169 ++++++++----------
 drivers/gpu/drm/bridge/lontium-lt9611uxc.c         |   3 +-
 drivers/gpu/drm/bridge/sii902x.c                   |   5 +-
 .../gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c    |   3 +-
 drivers/gpu/drm/display/Kconfig                    |   8 +
 drivers/gpu/drm/display/Makefile                   |   2 +
 drivers/gpu/drm/display/drm_bridge_connector.c     | 137 ++++++++++++++-
 drivers/gpu/drm/display/drm_hdmi_audio_helper.c    | 189 +++++++++++++++++++++
 drivers/gpu/drm/display/drm_hdmi_state_helper.c    |  56 ++++++
 drivers/gpu/drm/drm_connector.c                    |   5 +
 drivers/gpu/drm/exynos/exynos_hdmi.c               |   2 +-
 drivers/gpu/drm/i2c/tda998x_drv.c                  |   2 +-
 drivers/gpu/drm/mediatek/mtk_dp.c                  |   2 +-
 drivers/gpu/drm/mediatek/mtk_hdmi.c                |   2 +-
 drivers/gpu/drm/rockchip/cdn-dp-core.c             |   2 +-
 drivers/gpu/drm/sti/sti_hdmi.c                     |   2 +-
 drivers/gpu/drm/vc4/Kconfig                        |   1 +
 drivers/gpu/drm/vc4/vc4_hdmi.c                     | 103 +++--------
 drivers/gpu/drm/vc4/vc4_hdmi.h                     |   2 -
 include/drm/display/drm_hdmi_state_helper.h        |   5 +
 include/drm/drm_bridge.h                           |  74 ++++++++
 include/drm/drm_connector.h                        | 141 +++++++++++++++
 include/sound/hdmi-codec.h                         |   7 +-
 sound/soc/codecs/hdmi-codec.c                      |   4 +-
 27 files changed, 726 insertions(+), 208 deletions(-)
---
base-commit: 9d2616754ce7e16a9e73ab6c00efc27fe47cb943
change-id: 20240530-drm-bridge-hdmi-connector-9b0f6725973e

Best regards,
-- 
Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>