linux-kernel - [PATCH 2/4] ASoC: core: add support for dai-links with symmetric clock roles

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Date:   Fri,  2 Jun 2023 11:03:19 +0200
From:   Alvin Šipraga <alvin@...s.dk>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
Cc:     Alvin Šipraga <alsi@...g-olufsen.dk>,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] ASoC: core: add support for dai-links with symmetric clock roles

From: Alvin Šipraga <alsi@...g-olufsen.dk>

The snd_soc_dai_link::dai_fmt field contains the nominal bit- and
frame-clock consumer/provider role from the point of view of the codec.
The ASoC core then assumes that it should flip the roles when
initializing the format on the CPU. But in cases where both the CPU and
codec are clock consumers, e.g. because of an external clock source,
this assumption breaks down.

To allow for proper configuration of the backing CPU/codec drivers for
consumer roles, introduce support for a symmetric_clock_roles flag. The
role flipping will be skipped when this flag is set.

Signed-off-by: Alvin Šipraga <alsi@...g-olufsen.dk>
---
 include/sound/soc.h  | 3 +++
 sound/soc/soc-core.c | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 533e553a343f..87f4fb3d4b20 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -718,6 +718,9 @@ struct snd_soc_dai_link {
 	/* Keep DAI active over suspend */
 	unsigned int ignore_suspend:1;
 
+	/* Assume CPU/Codec have the same clock consumer/provider role */
+	unsigned int symmetric_clock_roles:1;
+
 	/* Symmetry requirements */
 	unsigned int symmetric_rate:1;
 	unsigned int symmetric_channels:1;
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index b48efc3a08d2..7817b86dd93d 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -1216,6 +1216,7 @@ static void snd_soc_runtime_get_dai_fmt(struct snd_soc_pcm_runtime *rtd)
 int snd_soc_runtime_set_dai_fmt(struct snd_soc_pcm_runtime *rtd,
 				unsigned int dai_fmt)
 {
+	struct snd_soc_dai_link *dai_link = rtd->dai_link;
 	struct snd_soc_dai *cpu_dai;
 	struct snd_soc_dai *codec_dai;
 	unsigned int i;
@@ -1231,7 +1232,8 @@ int snd_soc_runtime_set_dai_fmt(struct snd_soc_pcm_runtime *rtd,
 	}
 
 	/* Flip the polarity for the "CPU" end of link */
-	dai_fmt = snd_soc_daifmt_clock_provider_flipped(dai_fmt);
+	if (!dai_link->symmetric_clock_roles)
+		dai_fmt = snd_soc_daifmt_clock_provider_flipped(dai_fmt);
 
 	for_each_rtd_cpu_dais(rtd, i, cpu_dai) {
 		ret = snd_soc_dai_set_fmt(cpu_dai, dai_fmt);
-- 
2.40.0