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From: Wesley Cheng <quic_wcheng@quicinc.com>
To: <srinivas.kandagatla@linaro.org>, <mathias.nyman@intel.com>,
	<perex@perex.cz>, <conor+dt@kernel.org>, <corbet@lwn.net>,
	<lgirdwood@gmail.com>, <andersson@kernel.org>,
	<krzysztof.kozlowski+dt@linaro.org>, <gregkh@linuxfoundation.org>,
	<Thinh.Nguyen@synopsys.com>, <broonie@kernel.org>,
	<bgoswami@quicinc.com>, <tiwai@suse.com>, <robh@kernel.org>,
	<konrad.dybcio@linaro.org>
Cc: <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<linux-sound@vger.kernel.org>, <linux-usb@vger.kernel.org>,
	<linux-arm-msm@vger.kernel.org>, <linux-doc@vger.kernel.org>,
	<alsa-devel@alsa-project.org>,
	Wesley Cheng <quic_wcheng@quicinc.com>
Subject: [PATCH v20 24/41] ALSA: usb-audio: Prevent starting of audio stream if in use
Date: Thu, 25 Apr 2024 14:51:08 -0700	[thread overview]
Message-ID: <20240425215125.29761-25-quic_wcheng@quicinc.com> (raw)
In-Reply-To: <20240425215125.29761-1-quic_wcheng@quicinc.com>

With USB audio offloading, an audio session is started from the ASoC
platform sound card and PCM devices.  Likewise, the USB SND path is still
readily available for use, in case the non-offload path is desired.  In
order to prevent the two entities from attempting to use the USB bus,
introduce a flag that determines when either paths are in use.

If a PCM device is already in use, the check will return an error to
userspace notifying that the stream is currently busy.  This ensures that
only one path is using the USB substream.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
 sound/usb/card.h |  1 +
 sound/usb/pcm.c  | 29 ++++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/sound/usb/card.h b/sound/usb/card.h
index d66cc0b139af..3c900e5afbce 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -165,6 +165,7 @@ struct snd_usb_substream {
 	unsigned int pkt_offset_adj;	/* Bytes to drop from beginning of packets (for non-compliant devices) */
 	unsigned int stream_offset_adj;	/* Bytes to drop from beginning of stream (for non-compliant devices) */
 
+	unsigned int opened:1;		/* pcm device opened */
 	unsigned int running: 1;	/* running status */
 	unsigned int period_elapsed_pending;	/* delay period handling */
 
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 3adb09ce1702..3e6d33de6ce6 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1241,8 +1241,17 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream)
 	struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_usb_substream *subs = &as->substream[direction];
+	struct snd_usb_audio *chip = subs->stream->chip;
 	int ret;
 
+	mutex_lock(&chip->mutex);
+	if (subs->opened) {
+		mutex_unlock(&chip->mutex);
+		return -EBUSY;
+	}
+	subs->opened = 1;
+	mutex_unlock(&chip->mutex);
+
 	runtime->hw = snd_usb_hardware;
 	/* need an explicit sync to catch applptr update in low-latency mode */
 	if (direction == SNDRV_PCM_STREAM_PLAYBACK &&
@@ -1259,13 +1268,23 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream)
 
 	ret = setup_hw_info(runtime, subs);
 	if (ret < 0)
-		return ret;
+		goto err_open;
 	ret = snd_usb_autoresume(subs->stream->chip);
 	if (ret < 0)
-		return ret;
+		goto err_open;
 	ret = snd_media_stream_init(subs, as->pcm, direction);
 	if (ret < 0)
-		snd_usb_autosuspend(subs->stream->chip);
+		goto err_resume;
+
+	return 0;
+
+err_resume:
+	snd_usb_autosuspend(subs->stream->chip);
+err_open:
+	mutex_lock(&chip->mutex);
+	subs->opened = 0;
+	mutex_unlock(&chip->mutex);
+
 	return ret;
 }
 
@@ -1274,6 +1293,7 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream)
 	int direction = substream->stream;
 	struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
 	struct snd_usb_substream *subs = &as->substream[direction];
+	struct snd_usb_audio *chip = subs->stream->chip;
 	int ret;
 
 	snd_media_stop_pipeline(subs);
@@ -1287,6 +1307,9 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream)
 
 	subs->pcm_substream = NULL;
 	snd_usb_autosuspend(subs->stream->chip);
+	mutex_lock(&chip->mutex);
+	subs->opened = 0;
+	mutex_unlock(&chip->mutex);
 
 	return 0;
 }

  parent reply	other threads:[~2024-04-25 21:52 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-25 21:50 [PATCH v20 00/41] Introduce QC USB SND audio offloading support Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 01/41] xhci: add helper to stop endpoint and wait for completion Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 02/41] usb: host: xhci: Export enable and disable interrupter APIs Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 03/41] usb: host: xhci: Repurpose event handler for skipping interrupter events Wesley Cheng
2024-04-30 11:02   ` Mathias Nyman
2024-04-30 21:57     ` Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 04/41] xhci: export XHCI IMOD setting helper for interrupters Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 05/41] xhci: sideband: add initial api to register a sideband entity Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 06/41] usb: host: xhci-sideband: Expose a sideband interrupter enable API Wesley Cheng
2024-05-02 11:07   ` Mathias Nyman
2024-05-02 23:37     ` Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 07/41] usb: host: xhci-mem: Cleanup pending secondary event ring events Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 08/41] usb: host: xhci-mem: Allow for interrupter clients to choose specific index Wesley Cheng
2024-04-26 13:24   ` Amadeusz Sławiński
2024-04-26 20:03     ` Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 09/41] ASoC: Add SOC USB APIs for adding an USB backend Wesley Cheng
2024-04-26 13:25   ` Amadeusz Sławiński
2024-04-26 21:55     ` Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 10/41] ASoC: dt-bindings: qcom,q6dsp-lpass-ports: Add USB_RX port Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 11/41] ASoC: qcom: qdsp6: Introduce USB AFE port to q6dsp Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 12/41] ASoC: qdsp6: q6afe: Increase APR timeout Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 13/41] ASoC: qcom: qdsp6: Add USB backend ASoC driver for Q6 Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 14/41] ALSA: usb-audio: Introduce USB SND platform op callbacks Wesley Cheng
2024-04-25 21:50 ` [PATCH v20 15/41] ALSA: usb-audio: Export USB SND APIs for modules Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 16/41] ALSA: usb-audio: Save UAC sample size information Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 17/41] usb: dwc3: Specify maximum number of XHCI interrupters Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 18/41] usb: host: xhci-plat: Set XHCI max interrupters if property is present Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 19/41] ALSA: usb-audio: qcom: Add USB QMI definitions Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 20/41] ALSA: usb-audio: qcom: Introduce QC USB SND offloading support Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 21/41] ALSA: usb-audio: Check for support for requested audio format Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 22/41] ASoC: usb: Add PCM format check API for USB backend Wesley Cheng
2024-04-26 13:25   ` Amadeusz Sławiński
2024-04-30  8:01     ` Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 23/41] ASoC: qcom: qdsp6: Ensure PCM format is supported by USB audio device Wesley Cheng
2024-04-25 21:51 ` Wesley Cheng [this message]
2024-04-25 21:51 ` [PATCH v20 25/41] ALSA: usb-audio: Do not allow USB offload path if PCM device is in use Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 26/41] ASoC: dt-bindings: Update example for enabling USB offload on SM8250 Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 27/41] ALSA: usb-audio: qcom: Populate PCM and USB chip information Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 28/41] ASoC: qcom: qdsp6: Add support to track available USB PCM devices Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 29/41] ASoC: Introduce SND kcontrols to select sound card and PCM device Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 30/41] ASoC: qcom: qdsp6: Add SOC USB offload select get/put callbacks Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 31/41] ASoC: Introduce SND kcontrols to track USB offloading state Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 32/41] ASoC: qcom: qdsp6: Add PCM ops to track current state Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 33/41] ASoC: usb: Create SOC USB SND jack kcontrol Wesley Cheng
2024-04-26 13:26   ` Amadeusz Sławiński
2024-05-01  0:32     ` Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 34/41] ASoC: qcom: qdsp6: Add headphone jack for offload connection status Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 35/41] ASoC: usb: Fetch ASoC sound card information Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 36/41] ALSA: usb-audio: Add USB offloading capable kcontrol Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 37/41] ALSA: usb-audio: Allow for rediscovery of connected USB SND devices Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 38/41] ALSA: usb-audio: qcom: Use card and PCM index from QMI request Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 39/41] ASoC: usb: Rediscover USB SND devices on USB port add Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 40/41] ASoC: qcom: Populate SoC components string Wesley Cheng
2024-04-25 21:51 ` [PATCH v20 41/41] ASoC: doc: Add documentation for SOC USB Wesley Cheng
2024-04-26  3:36   ` Bagas Sanjaya

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