Re: [PATCH v6] drm/bridge: dw-hdmi-qp: serialize HDMI audio callbacks with PHY enable/disable

[Igor Paunovic <royalnet026@gmail.com>]

Hi Frank,

I tested v6 on an Orange Pi 5 Plus (RK3588): git am onto a
drm-misc-next based 7.3.0-rc2 tree with PROVE_LOCKING and
DEBUG_ATOMIC_SLEEP, HDMI output to a TV.

The reproducer I used on v5 (output off, then open and close the PCM)
now stops at the open: dw_hdmi_qp_audio_enable() returned -EOPNOTSUPP
three times out of three, nothing from ASoC or the bridge was logged,
and since the startup failed, the shutdown path never reached
clear_audio_infoframe().

So I also ran the sequence from your commit message: PCM opened with
the output on, output turned off by the compositor while the stream
runs, PCM closed after that. With function_graph on
dw_hdmi_qp_bridge_clear_audio_infoframe() and
dw_hdmi_qp_audio_enable(), the clear call after the disable takes and
drops phy.lock and returns 0 with no regmap access inside it; with the
output on, as a control, one regmap_update_bits_base() call shows up
inside it, under the lock.

There was no external abort, SError, lockdep report or might_sleep
splat in the whole run, including two output off/on cycles, and once
the output was back on a new stream played on the TV.

Tested-by: Igor Paunovic <royalnet026@gmail.com> # Orange Pi 5 Plus (RK3588)

Not covered: I did not try to hit the window the lock is meant to
close (an atomic disable landing between the state check and a
register write), so that part rests on the code; and I did not check
Dmitry's condition from v2 [1] that a PHY off/on cycle clears the
audio registers.

v6 overlaps with Detlev's patch [2] (both return -EOPNOTSUPP from the
audio callbacks while the output is off), and [2] no longer applies on
top of v6. For the crash, v6 alone now covers both sequences from my
v5 note (open with the output already off, and the output going away
under an open PCM), so my remark there that both patches are needed
does not apply to v6.

An LLM assistant applied and built the patch, wrote the test scripts,
counted the traces and helped draft this mail; I ran the tests on the
board and did the listening myself.

[1] https://lore.kernel.org/all/urguajogb4zsz4jg3ef32hpyf2awxkywdtlk5ackdi2gjai4l7@vpjaf3sznkto/
[2] https://lore.kernel.org/all/20260519-fix-hdmi-audio-warnings-v1-1-9608966c993f@collabora.com/

Igor