[PATCH v4 0/4] media: synopsys: hdmirx: add HDMI audio capture support

[Igor Paunovic <royalnet026@gmail.com>]

This series adds audio capture support to the Synopsys DesignWare HDMI
RX controller used on the Rockchip RK3588: the controller's audio FIFO
is exposed through an ASoC hdmi-codec device, with a periodic worker
that keeps the local audio clock locked to the incoming stream by
tracking the FIFO fill level. Together with the two dts patches this
yields a capture-only ALSA card fed by the HDMI input.

Validated on the Orange Pi 5 Plus against multiple HDMI sources:
capture follows the source sample rate (44.1/48 kHz switches
included), survives repeated stream start/stop cycles and SIGKILL of
the capturing process, stays free of FIFO under/overruns via the
clock tracking, and now also survives system suspend with an active
capture stream: audio resumes flowing on its own after the cycle.

Changes in v4:
- Driver: support system suspend instead of the -EBUSY guard
  discussed on the v3 thread (Dmitry Osipenko's preference). The
  worker is stopped before the controller clocks are gated; resume
  fully resets the controller, so the audio path is re-programmed
  from the last known sample rate and the worker re-armed while a
  capture stream is active, through a hdmirx_audio_setup() helper
  shared with hw_params(). Validated with an active capture stream
  across the suspend/resume cycle.
- Driver: use swab32() for the ACR word reversal; readl() already
  abstracts bus endianness, so the reversal must be unconditional
  (automated review, valid finding)
- dts: the sound card is now a shared, disabled-by-default
  "RK3588 HDMI-IN" node in rk3588-extra.dtsi, mirroring the HDMI TX
  sound cards; the board patch only flips it on (Sebastian Reichel)
- binding: reference dai-common.yaml, switch to
  unevaluatedProperties: false, and drop the consumer comment from
  the example (Krzysztof Kozlowski)

Known limitation, noted on the v3 thread and under investigation as a
follow-up: a second suspend/resume cycle in the same boot can leave
the audio datapath silent until reboot. It reproduces with no-stream
suspend cycles as well, so it is independent of the suspend handling
added here, and looks related to the cold-start behavior described in
the v3 testing notes.

Link to v3: https://lore.kernel.org/linux-media/20260718085728.6797-1-royalnet026@gmail.com/
Link to v2: https://lore.kernel.org/linux-media/20260715200834.8486-1-royalnet026@gmail.com/
Link to v1 (RFC): https://lore.kernel.org/linux-media/20260715051939.64652-1-royalnet026@gmail.com/

Igor Paunovic (4):
  dt-bindings: media: snps,dw-hdmi-rx: add #sound-dai-cells
  media: synopsys: hdmirx: add HDMI audio capture support
  arm64: dts: rockchip: add HDMI RX audio on RK3588
  arm64: dts: rockchip: enable HDMI RX audio capture on Orange Pi 5 Plus

 .../bindings/media/snps,dw-hdmi-rx.yaml       |  13 +-
 .../arm64/boot/dts/rockchip/rk3588-extra.dtsi |  18 ++
 .../dts/rockchip/rk3588-orangepi-5-plus.dts   |   8 +
 .../platform/synopsys/hdmirx/snps_hdmirx.c    | 306 ++++++++++++++++++
 .../platform/synopsys/hdmirx/snps_hdmirx.h    |   8 +
 5 files changed, 352 insertions(+), 1 deletion(-)

-- 
2.53.0