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drm/vc4: hdmi: Allow audio PCM open/prepare without a connected sink #7495

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drm/vc4: hdmi: Allow audio PCM open/prepare without a connected sink #7495

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30 changes: 24 additions & 6 deletions drivers/gpu/drm/vc4/vc4_hdmi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1921,10 +1921,13 @@ static int vc4_hdmi_audio_startup(struct drm_connector *connector)
goto out;
}

if (!vc4_hdmi_audio_can_stream(vc4_hdmi)) {
ret = -ENOTSUPP;
/*
* Allow the PCM to open with no sink connected so userspace can probe
* the card profile at start-up. Touch no hardware here (the HDMI block
* may be runtime suspended); streaming is gated in audio_prepare().
*/
if (!vc4_hdmi_audio_can_stream(vc4_hdmi))
goto out_dev_exit;
}

vc4_hdmi->audio.streaming = true;

Expand Down Expand Up @@ -1982,6 +1985,16 @@ static void vc4_hdmi_audio_shutdown(struct drm_connector *connector)
if (!drm_dev_enter(drm, &idx))
goto out;

/*
* Nothing was programmed if streaming never started (e.g. PCM opened
* only for profile probing); the HDMI block may be powered down, so
* avoid register access.
*/
if (!vc4_hdmi->audio.streaming) {
drm_dev_exit(idx);
goto out;
}

spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);

HDMI_WRITE(HDMI_MAI_CTL,
Expand Down Expand Up @@ -2069,10 +2082,15 @@ static int vc4_hdmi_audio_prepare(struct drm_connector *connector,
goto out;
}

if (!vc4_hdmi_audio_can_stream(vc4_hdmi)) {
ret = -EINVAL;
/*
* Let .prepare succeed with no sink connected: snd_pcm_hw_params()
* implicitly prepares, which userspace issues when probing the card
* profile. Failing here would drop the HDMI profile on a headless
* boot. Touch no hardware (the HDMI block may be runtime suspended);
* the MAI is programmed once a sink connects and streaming starts.
*/
if (!vc4_hdmi_audio_can_stream(vc4_hdmi))
goto out_dev_exit;
}

vc4_hdmi_audio_set_mai_clock(vc4_hdmi, sample_rate);

Expand Down