linux-kernel - [RFC PATCH v2 17/22] sound: usb: card: Check for support for requested audio format

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Message-ID: <20230126031424.14582-18-quic_wcheng@quicinc.com>
Date:   Wed, 25 Jan 2023 19:14:19 -0800
From:   Wesley Cheng <quic_wcheng@...cinc.com>
To:     <srinivas.kandagatla@...aro.org>, <mathias.nyman@...el.com>,
        <perex@...ex.cz>, <lgirdwood@...il.com>, <andersson@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <gregkh@...uxfoundation.org>,
        <Thinh.Nguyen@...opsys.com>, <broonie@...nel.org>,
        <bgoswami@...cinc.com>, <tiwai@...e.com>, <robh+dt@...nel.org>,
        <agross@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <alsa-devel@...a-project.org>, <devicetree@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <quic_jackp@...cinc.com>,
        <quic_plai@...cinc.com>, Wesley Cheng <quic_wcheng@...cinc.com>
Subject: [RFC PATCH v2 17/22] sound: usb: card: Check for support for requested audio format

Allow for checks on a specific USB audio device to see if a requested PCM
format is supported.  This is needed for support for when playback is
initiated by the ASoC USB backend path.

Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 sound/usb/card.c | 28 ++++++++++++++++++++++++++++
 sound/usb/card.h |  8 ++++++++
 2 files changed, 36 insertions(+)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 59be5f543315..be06d19ee935 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -136,6 +136,34 @@ int snd_usb_unregister_platform_ops(void)
 }
 EXPORT_SYMBOL_GPL(snd_usb_unregister_platform_ops);
 
+struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx,
+			struct snd_pcm_hw_params *params, int direction)
+{
+	struct snd_usb_audio *chip = usb_chip[card_idx];
+	struct snd_usb_substream *subs = NULL;
+	struct snd_usb_stream *as;
+	const struct audioformat *fmt;
+
+	if (!chip)
+		return NULL;
+
+	mutex_lock(&chip->mutex);
+	if (enable[card_idx]) {
+		list_for_each_entry(as, &chip->pcm_list, list) {
+			subs = &as->substream[direction];
+			fmt = find_substream_format(subs, params);
+			if (fmt) {
+				mutex_unlock(&chip->mutex);
+				return as;
+			}
+		}
+	}
+	mutex_unlock(&chip->mutex);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(snd_usb_find_suppported_substream);
+
 /*
  * disconnect streams
  * called from usb_audio_disconnect()
diff --git a/sound/usb/card.h b/sound/usb/card.h
index 2249c411c3a1..410a4ffad98e 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -215,6 +215,8 @@ struct snd_usb_platform_ops {
 #if IS_ENABLED(CONFIG_SND_USB_AUDIO)
 int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops);
 int snd_usb_unregister_platform_ops(void);
+struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx,
+			struct snd_pcm_hw_params *params, int direction);
 #else
 int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops)
 {
@@ -225,5 +227,11 @@ int snd_usb_unregister_platform_ops(void)
 {
 	return -EOPNOTSUPP;
 }
+
+struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx,
+			struct snd_pcm_hw_params *params, int direction)
+{
+	return NULL;
+}
 #endif /* IS_ENABLED(CONFIG_SND_USB_AUDIO) */
 #endif /* __USBAUDIO_CARD_H */