linux-kernel - [PATCH v2 3/9] ASoC: audio-graph: Identify 'no

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Date:   Wed, 5 Aug 2020 10:54:18 +0530
From:   Sameer Pujar <spujar@...dia.com>
To:     <broonie@...nel.org>, <perex@...ex.cz>, <tiwai@...e.com>,
        <kuninori.morimoto.gx@...esas.com>, <robh+dt@...nel.org>,
        <lgirdwood@...il.com>
CC:     <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <alsa-devel@...a-project.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <sharadg@...dia.com>,
        <mkumard@...dia.com>, <viswanathl@...dia.com>,
        <rlokhande@...dia.com>, <dramesh@...dia.com>,
        <atalambedu@...dia.com>, <nwartikar@...dia.com>,
        <swarren@...dia.com>, <nicoleotsuka@...il.com>,
        Sameer Pujar <spujar@...dia.com>
Subject: [PATCH v2 3/9] ASoC: audio-graph: Identify 'no_pcm' DAI links for DPCM

PCM devices are created for FE dai links with 'no-pcm' flag as '0'.
Such DAI links have CPU component which implement either pcm_construct()
or pcm_new() at component or dai level respectively. Based on this,
current patch exposes a helper function to identify such components
and populate 'no_pcm' flag for DPCM DAI link.

This helps to have BE<->BE component links where PCM devices need
not be created for CPU component involved in such links.

Signed-off-by: Sameer Pujar <spujar@...dia.com>
---
 sound/soc/generic/audio-graph-card.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/sound/soc/generic/audio-graph-card.c b/sound/soc/generic/audio-graph-card.c
index 1e20562..93bddf6 100644
--- a/sound/soc/generic/audio-graph-card.c
+++ b/sound/soc/generic/audio-graph-card.c
@@ -111,6 +111,17 @@ static int graph_get_dai_id(struct device_node *ep)
 	return id;
 }
 
+static bool soc_component_is_pcm(struct snd_soc_dai_link_component *dlc)
+{
+	struct snd_soc_dai *dai = snd_soc_find_dai(dlc);
+
+	if (dai && (dai->component->driver->pcm_construct ||
+		    dai->driver->pcm_new))
+		return true;
+
+	return false;
+}
+
 static int asoc_simple_parse_dai(struct device_node *ep,
 				 struct snd_soc_dai_link_component *dlc,
 				 int *is_single_link)
@@ -259,6 +270,16 @@ static int graph_dai_link_of_dpcm(struct asoc_simple_priv *priv,
 		if (ret < 0)
 			goto out_put_node;
 
+		/*
+		 * In BE<->BE connections it is not required to create
+		 * PCM devices at CPU end of the dai link and thus 'no_pcm'
+		 * flag needs to be set. It is useful when there are many
+		 * BE components and some of these have to be connected to
+		 * form a valid audio path.
+		 */
+		if (!soc_component_is_pcm(cpus))
+			dai_link->no_pcm = 1;
+
 		/* card->num_links includes Codec */
 		asoc_simple_canonicalize_cpu(dai_link, is_single_links);
 	} else {
-- 
2.7.4