sound: usb: Send explicit device disconnect to clients

Explicitly send device disconnect notification to client
so that client can disable audio streams. This will in turn
enable sound usb driver to release usb device and notify device
removal to user-space. User-space will clean up audio session.
Without this change sound usb driver is blocking usb device
release till audio streams are disabled. However, audio streams
are only disabled when user-space cleans up audio session on usb
device removal which is blocked. This change is trying to fix
this deadlock condition by notifying device disconnect to clients
explicitly.

Change-Id: I7e5a8aca84a7a620bb61eb0ace8a6b6c622f89de
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>

2 files changed, 36 insertions, 11 deletions

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 524688e4c144..1f6c247f773a 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -673,6 +673,9 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 
 	card = chip->card;
 
+	if (chip->disconnect_cb)
+		chip->disconnect_cb(chip);
+
 	mutex_lock(&register_mutex);
 	if (atomic_inc_return(&chip->shutdown) == 1) {
 		struct snd_usb_stream *as;
@@ -707,8 +710,6 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 	if (chip->num_interfaces <= 0) {
 		usb_chip[chip->index] = NULL;
 		mutex_unlock(&register_mutex);
-		if (chip->disconnect_cb)
-			chip->disconnect_cb(chip);
 		snd_card_free_when_closed(card);
 	} else {
 		mutex_unlock(&register_mutex);
diff --git a/sound/usb/usb_audio_qmi_svc.c b/sound/usb/usb_audio_qmi_svc.c
index fa0206cc14c6..8337d11bad12 100644
--- a/sound/usb/usb_audio_qmi_svc.c
+++ b/sound/usb/usb_audio_qmi_svc.c
@@ -134,6 +134,12 @@ static struct msg_desc uaudio_stream_resp_desc = {
 	.ei_array = qmi_uaudio_stream_resp_msg_v01_ei,
 };
 
+static struct msg_desc uaudio_stream_ind_desc = {
+	.max_msg_len = QMI_UAUDIO_STREAM_IND_MSG_V01_MAX_MSG_LEN,
+	.msg_id = QMI_UADUIO_STREAM_IND_V01,
+	.ei_array = qmi_uaudio_stream_ind_msg_v01_ei,
+};
+
 enum mem_type {
 	MEM_EVENT_RING,
 	MEM_DCBA,
@@ -643,29 +649,47 @@ void uaudio_disconnect_cb(struct snd_usb_audio *chip)
 	int ret, if_idx;
 	struct uaudio_dev *dev;
 	int card_num = chip->card_num;
+	struct uaudio_qmi_svc *svc = uaudio_svc;
+	struct qmi_uaudio_stream_ind_msg_v01 disconnect_ind = {0};
 
 	pr_debug("%s: for card# %d\n", __func__, card_num);
 
-	mutex_lock(&chip->dev_lock);
 	if (card_num >=  SNDRV_CARDS) {
 		pr_err("%s: invalid card number\n", __func__);
-		goto done;
+		return;
 	}
 
+	mutex_lock(&chip->dev_lock);
 	dev = &uadev[card_num];
+
+	/* clean up */
+	if (!dev->udev) {
+		pr_debug("%s: no clean up required\n", __func__);
+		goto done;
+	}
+
 	if (atomic_read(&dev->in_use)) {
+		mutex_unlock(&chip->dev_lock);
+
+		pr_debug("%s: sending qmi indication disconnect\n", __func__);
+		disconnect_ind.dev_event = USB_AUDIO_DEV_DISCONNECT_V01;
+		disconnect_ind.slot_id = dev->udev->slot_id;
+		ret = qmi_send_ind(svc->uaudio_svc_hdl, svc->curr_conn,
+				&uaudio_stream_ind_desc, &disconnect_ind,
+				sizeof(disconnect_ind));
+		if (ret < 0) {
+			pr_err("%s: qmi send failed wiht err: %d\n",
+					__func__, ret);
+			return;
+		}
+
 		ret = wait_event_interruptible(dev->disconnect_wq,
 				!atomic_read(&dev->in_use));
 		if (ret < 0) {
 			pr_debug("%s: failed with ret %d\n", __func__, ret);
-			goto done;
+			return;
 		}
-	}
-
-	/* clean up */
-	if (!dev->udev) {
-		pr_debug("%s: no clean up required\n", __func__);
-		goto done;
+		mutex_lock(&chip->dev_lock);
 	}
 
 	/* free xfer buffer and unmap xfer ring and buf per interface */