[PATCH RFC] drm/vc4: hdmi: Avoid ASoC error messages on startup

[Stefan Wahren]

During startup of Raspberry Pi 4 there seems to be a race between
VC4 probing and Pulseaudio trying to open its PCM device:

    ASoC: error at snd_soc_dai_startup on fef05700.hdmi: -19

Avoid these errors by returning EPROBE_DEFER in this situation.

Signed-off-by: Stefan Wahren <stefan.wahren at i2se.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 5551062..e0f9357 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -909,12 +909,14 @@ static int vc4_hdmi_audio_startup(struct snd_pcm_substream *substream,
 
 	vc4_hdmi->audio.substream = substream;
 
+	if (!encoder->crtc)
+		return -EPROBE_DEFER;
+
 	/*
-	 * If the HDMI encoder hasn't probed, or the encoder is
-	 * currently in DVI mode, treat the codec dai as missing.
+	 * If the HDMI encoder is currently in DVI mode,
+	 * treat the codec dai as missing.
 	 */
-	if (!encoder->crtc || !(HDMI_READ(HDMI_RAM_PACKET_CONFIG) &
-				VC4_HDMI_RAM_PACKET_ENABLE))
+	if (!(HDMI_READ(HDMI_RAM_PACKET_CONFIG) & VC4_HDMI_RAM_PACKET_ENABLE))
 		return -ENODEV;
 
 	ret = snd_pcm_hw_constraint_eld(substream->runtime, connector->eld);
-- 
2.7.4