[PATCH RFC v2 0/7] 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.

This series is in the RFC stage, so some bits are underdocumented.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
---
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@linaro.org

---
Dmitry Baryshkov (7):
      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 codec 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 connector update functions
      drm/bridge_connector: hook __drm_atomic_helper_connector_hdmi_update_edid()

 drivers/gpu/drm/Makefile                           |   1 +
 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            | 170 ++++++++-----------
 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/drm_bridge_connector.c     | 160 ++++++++++++++++--
 drivers/gpu/drm/display/drm_hdmi_state_helper.c    |  56 +++++++
 drivers/gpu/drm/drm_connector.c                    |  10 ++
 drivers/gpu/drm/drm_connector_hdmi_codec.c         | 186 +++++++++++++++++++++
 drivers/gpu/drm/drm_internal.h                     |   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 +-
 include/drm/display/drm_hdmi_state_helper.h        |   4 +
 include/drm/drm_bridge.h                           |  23 +++
 include/drm/drm_connector.h                        |  80 +++++++++
 include/sound/hdmi-codec.h                         |   7 +-
 sound/soc/codecs/hdmi-codec.c                      |   4 +-
 24 files changed, 601 insertions(+), 136 deletions(-)
---
base-commit: f9f24ca362a4d84dd8aeb4b8f3ec28cb6c43dd06
change-id: 20240530-drm-bridge-hdmi-connector-9b0f6725973e

Best regards,
-- 
Dmitry Baryshkov <dmitry.baryshkov at linaro.org>