linux-kernel - [PATCH] ASoC: hdmi-codec: fix channel info for compressed formats

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Date:   Sat, 24 Jun 2023 18:52:32 +0200
From:   Matthias Reichl <hias@...us.com>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
Cc:     Matthias Reichl <hias@...us.com>,
        Dom Cobley <popcornmix@...il.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] ASoC: hdmi-codec: fix channel info for compressed formats

According to CTA 861 the channel/speaker allocation info in the
audio infoframe only applies to uncompressed (PCM) audio streams.

The channel count info should indicate the number of channels
in the transmitted audio, which usually won't match the number of
channels used to transmit the compressed bitstream.

Some devices (eg some Sony TVs) will refuse to decode compressed
audio if these values are not set correctly.

To fix this we can simply set the channel count to 0 (which means
"refer to stream header") and set the channel/speaker allocation to 0
as well (which would mean stereo FL/FR for PCM, a safe value all sinks
will support) when transmitting compressed audio.

Signed-off-by: Matthias Reichl <hias@...us.com>
---
 sound/soc/codecs/hdmi-codec.c | 36 +++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index 6d980fbc42077..d21f69f053422 100644
--- a/sound/soc/codecs/hdmi-codec.c
+++ b/sound/soc/codecs/hdmi-codec.c
@@ -495,31 +495,43 @@ static int hdmi_codec_fill_codec_params(struct snd_soc_dai *dai,
 					struct hdmi_codec_params *hp)
 {
 	struct hdmi_codec_priv *hcp = snd_soc_dai_get_drvdata(dai);
-	int idx;
-
-	/* Select a channel allocation that matches with ELD and pcm channels */
-	idx = hdmi_codec_get_ch_alloc_table_idx(hcp, channels);
-	if (idx < 0) {
-		dev_err(dai->dev, "Not able to map channels to speakers (%d)\n",
-			idx);
-		hcp->chmap_idx = HDMI_CODEC_CHMAP_IDX_UNKNOWN;
-		return idx;
+	int idx = HDMI_CODEC_CHMAP_IDX_UNKNOWN;
+	u8 ca_id = 0;
+	bool pcm_audio = !(hcp->iec_status[0] & IEC958_AES0_NONAUDIO);
+
+	if (pcm_audio) {
+		/* Select a channel allocation that matches with ELD and pcm channels */
+		idx = hdmi_codec_get_ch_alloc_table_idx(hcp, channels);
+
+		if (idx < 0) {
+			dev_err(dai->dev, "Not able to map channels to speakers (%d)\n",
+				idx);
+			hcp->chmap_idx = HDMI_CODEC_CHMAP_IDX_UNKNOWN;
+			return idx;
+		}
+
+		ca_id = hdmi_codec_channel_alloc[idx].ca_id;
 	}
 
 	memset(hp, 0, sizeof(*hp));
 
 	hdmi_audio_infoframe_init(&hp->cea);
-	hp->cea.channels = channels;
+
+	if (pcm_audio)
+		hp->cea.channels = channels;
+	else
+		hp->cea.channels = 0;
+
 	hp->cea.coding_type = HDMI_AUDIO_CODING_TYPE_STREAM;
 	hp->cea.sample_size = HDMI_AUDIO_SAMPLE_SIZE_STREAM;
 	hp->cea.sample_frequency = HDMI_AUDIO_SAMPLE_FREQUENCY_STREAM;
-	hp->cea.channel_allocation = hdmi_codec_channel_alloc[idx].ca_id;
+	hp->cea.channel_allocation = ca_id;
 
 	hp->sample_width = sample_width;
 	hp->sample_rate = sample_rate;
 	hp->channels = channels;
 
-	hcp->chmap_idx = hdmi_codec_channel_alloc[idx].ca_id;
+	hcp->chmap_idx = idx;
 
 	return 0;
 }
-- 
2.39.2