[PATCH v7 3/3] sound/usb: Use Media Controller API to share media resources

From: Shuah Khan
Date: Tue Dec 06 2016 - 20:20:28 EST

Change ALSA driver to use Media Controller API to share media resources
with DVB, and V4L2 drivers on a AU0828 media device.

Media Controller specific initialization is done after sound card is
registered. ALSA creates Media interface and entity function graph
nodes for Control, Mixer, PCM Playback, and PCM Capture devices.

snd_usb_hw_params() will call Media Controller enable source handler
interface to request the media resource. If resource request is granted,
it will release it from snd_usb_hw_free(). If resource is busy, -EBUSY is
returned.

Media specific cleanup is done in usb_audio_disconnect().

Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
---
Changes to patch 0003 since v6:
- Addressed Takashi's review comments on patch v6

sound/usb/Kconfig | 4 +
sound/usb/Makefile | 2 +
sound/usb/card.c | 14 +++
sound/usb/card.h | 3 +
sound/usb/media.c | 321 +++++++++++++++++++++++++++++++++++++++++++++++
sound/usb/media.h | 73 +++++++++++
sound/usb/mixer.h | 3 +
sound/usb/pcm.c | 29 ++++-
sound/usb/quirks-table.h | 1 +
sound/usb/stream.c | 2 +
sound/usb/usbaudio.h | 6 +
11 files changed, 453 insertions(+), 5 deletions(-)
create mode 100644 sound/usb/media.c
create mode 100644 sound/usb/media.h

diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig
index a452ad7..d14bf41 100644
--- a/sound/usb/Kconfig
+++ b/sound/usb/Kconfig
@@ -15,6 +15,7 @@ config SND_USB_AUDIO
select SND_RAWMIDI
select SND_PCM
select BITREVERSE
+ select SND_USB_AUDIO_USE_MEDIA_CONTROLLER if MEDIA_CONTROLLER && (MEDIA_SUPPORT=y || MEDIA_SUPPORT=SND_USB_AUDIO)
help
Say Y here to include support for USB audio and USB MIDI
devices.
@@ -22,6 +23,9 @@ config SND_USB_AUDIO
To compile this driver as a module, choose M here: the module
will be called snd-usb-audio.

+config SND_USB_AUDIO_USE_MEDIA_CONTROLLER
+ bool
+
config SND_USB_UA101
tristate "Edirol UA-101/UA-1000 driver"
select SND_PCM
diff --git a/sound/usb/Makefile b/sound/usb/Makefile
index 2d2d122..8dca3c4 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile
@@ -15,6 +15,8 @@ snd-usb-audio-objs := card.o \
quirks.o \
stream.o

+snd-usb-audio-$(CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER) += media.o
+
snd-usbmidi-lib-objs := midi.o

# Toplevel Module Dependency
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 2ddc034..570ff00 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -66,6 +66,7 @@
#include "format.h"
#include "power.h"
#include "stream.h"
+#include "media.h"

MODULE_AUTHOR("Takashi Iwai <tiwai@xxxxxxx>");
MODULE_DESCRIPTION("USB Audio");
@@ -616,6 +617,11 @@ static int usb_audio_probe(struct usb_interface *intf,
if (err < 0)
goto __error;

+ if (quirk && quirk->media_device) {
+ /* don't want to fail when media_snd_device_create() fails */
+ media_snd_device_create(chip, intf);
+ }
+
usb_chip[chip->index] = chip;
chip->num_interfaces++;
usb_set_intfdata(intf, chip);
@@ -672,6 +678,14 @@ static void usb_audio_disconnect(struct usb_interface *intf)
list_for_each(p, &chip->midi_list) {
snd_usbmidi_disconnect(p);
}
+ /*
+ * Nice to check quirk && quirk->media_device and
+ * then call media_snd_device_delete(). Don't have
+ * access to quirk here. media_snd_device_delete()
+ * acceses mixer_list
+ */
+ media_snd_device_delete(chip);
+
/* release mixer resources */
list_for_each_entry(mixer, &chip->mixer_list, list) {
snd_usb_mixer_disconnect(mixer);
diff --git a/sound/usb/card.h b/sound/usb/card.h
index 111b0f0..6ef8e88 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -105,6 +105,8 @@ struct snd_usb_endpoint {
struct list_head list;
};

+struct media_ctl;
+
struct snd_usb_substream {
struct snd_usb_stream *stream;
struct usb_device *dev;
@@ -156,6 +158,7 @@ struct snd_usb_substream {
} dsd_dop;

bool trigger_tstamp_pending_update; /* trigger timestamp being updated from initial estimate */
+ struct media_ctl *media_ctl;
};

struct snd_usb_stream {
diff --git a/sound/usb/media.c b/sound/usb/media.c
new file mode 100644
index 0000000..0a8fc14
--- /dev/null
+++ b/sound/usb/media.c
@@ -0,0 +1,321 @@
+/*
+ * media.c - Media Controller specific ALSA driver code
+ *
+ * Copyright (c) 2016 Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
+ * Copyright (c) 2016 Samsung Electronics Co., Ltd.
+ *
+ * This file is released under the GPLv2.
+ */
+
+/*
+ * This file adds Media Controller support to ALSA driver
+ * to use the Media Controller API to share tuner with DVB
+ * and V4L2 drivers that control media device. Media device
+ * is created based on existing quirks framework. Using this
+ * approach, the media controller API usage can be added for
+ * a specific device.
+ */
+
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include <sound/pcm.h>
+#include <sound/core.h>
+
+#include "usbaudio.h"
+#include "card.h"
+#include "mixer.h"
+#include "media.h"
+
+int media_snd_stream_init(struct snd_usb_substream *subs, struct snd_pcm *pcm,
+ int stream)
+{
+ struct media_device *mdev;
+ struct media_ctl *mctl;
+ struct device *pcm_dev = &pcm->streams[stream].dev;
+ u32 intf_type;
+ int ret = 0;
+ u16 mixer_pad;
+ struct media_entity *entity;
+
+ mdev = subs->stream->chip->media_dev;
+ if (!mdev)
+ return 0;
+
+ if (subs->media_ctl)
+ return 0;
+
+ /* allocate media_ctl */
+ mctl = kzalloc(sizeof(*mctl), GFP_KERNEL);
+ if (!mctl)
+ return -ENOMEM;
+
+ mctl->media_dev = mdev;
+ if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
+ intf_type = MEDIA_INTF_T_ALSA_PCM_PLAYBACK;
+ mctl->media_entity.function = MEDIA_ENT_F_AUDIO_PLAYBACK;
+ mctl->media_pad.flags = MEDIA_PAD_FL_SOURCE;
+ mixer_pad = 1;
+ } else {
+ intf_type = MEDIA_INTF_T_ALSA_PCM_CAPTURE;
+ mctl->media_entity.function = MEDIA_ENT_F_AUDIO_CAPTURE;
+ mctl->media_pad.flags = MEDIA_PAD_FL_SINK;
+ mixer_pad = 2;
+ }
+ mctl->media_entity.name = pcm->name;
+ media_entity_pads_init(&mctl->media_entity, 1, &mctl->media_pad);
+ ret = media_device_register_entity(mctl->media_dev,
+ &mctl->media_entity);
+ if (ret)
+ goto free_mctl;
+
+ mctl->intf_devnode = media_devnode_create(mdev, intf_type, 0,
+ MAJOR(pcm_dev->devt),
+ MINOR(pcm_dev->devt));
+ if (!mctl->intf_devnode) {
+ ret = -ENOMEM;
+ goto unregister_entity;
+ }
+ mctl->intf_link = media_create_intf_link(&mctl->media_entity,
+ &mctl->intf_devnode->intf,
+ MEDIA_LNK_FL_ENABLED);
+ if (!mctl->intf_link) {
+ ret = -ENOMEM;
+ goto devnode_remove;
+ }
+
+ /* create link between mixer and audio */
+ media_device_for_each_entity(entity, mdev) {
+ switch (entity->function) {
+ case MEDIA_ENT_F_AUDIO_MIXER:
+ ret = media_create_pad_link(entity, mixer_pad,
+ &mctl->media_entity, 0,
+ MEDIA_LNK_FL_ENABLED);
+ if (ret)
+ goto remove_intf_link;
+ break;
+ }
+ }
+
+ subs->media_ctl = mctl;
+ return 0;
+
+remove_intf_link:
+ media_remove_intf_link(mctl->intf_link);
+devnode_remove:
+ media_devnode_remove(mctl->intf_devnode);
+unregister_entity:
+ media_device_unregister_entity(&mctl->media_entity);
+free_mctl:
+ kfree(mctl);
+ return ret;
+}
+
+void media_snd_stream_delete(struct snd_usb_substream *subs)
+{
+ struct media_ctl *mctl = subs->media_ctl;
+
+ if (mctl) {
+ struct media_device *mdev;
+
+ mdev = mctl->media_dev;
+ if (mdev && media_devnode_is_registered(mdev->devnode)) {
+ media_devnode_remove(mctl->intf_devnode);
+ media_device_unregister_entity(&mctl->media_entity);
+ media_entity_cleanup(&mctl->media_entity);
+ }
+ kfree(mctl);
+ subs->media_ctl = NULL;
+ }
+}
+
+int media_snd_start_pipeline(struct snd_usb_substream *subs)
+{
+ struct media_ctl *mctl = subs->media_ctl;
+ int ret = 0;
+
+ if (!mctl)
+ return 0;
+
+ mutex_lock(&mctl->media_dev->graph_mutex);
+ if (mctl->media_dev->enable_source)
+ ret = mctl->media_dev->enable_source(&mctl->media_entity,
+ &mctl->media_pipe);
+ mutex_unlock(&mctl->media_dev->graph_mutex);
+ return ret;
+}
+
+void media_snd_stop_pipeline(struct snd_usb_substream *subs)
+{
+ struct media_ctl *mctl = subs->media_ctl;
+
+ if (!mctl)
+ return;
+
+ mutex_lock(&mctl->media_dev->graph_mutex);
+ if (mctl->media_dev->disable_source)
+ mctl->media_dev->disable_source(&mctl->media_entity);
+ mutex_unlock(&mctl->media_dev->graph_mutex);
+}
+
+static int media_snd_mixer_init(struct snd_usb_audio *chip)
+{
+ struct device *ctl_dev = &chip->card->ctl_dev;
+ struct media_intf_devnode *ctl_intf;
+ struct usb_mixer_interface *mixer;
+ struct media_device *mdev = chip->media_dev;
+ struct media_mixer_ctl *mctl;
+ u32 intf_type = MEDIA_INTF_T_ALSA_CONTROL;
+ int ret;
+
+ if (!mdev)
+ return -ENODEV;
+
+ ctl_intf = chip->ctl_intf_media_devnode;
+ if (!ctl_intf) {
+ ctl_intf = media_devnode_create(mdev, intf_type, 0,
+ MAJOR(ctl_dev->devt),
+ MINOR(ctl_dev->devt));
+ if (!ctl_intf)
+ return -ENOMEM;
+ chip->ctl_intf_media_devnode = ctl_intf;
+ }
+
+ list_for_each_entry(mixer, &chip->mixer_list, list) {
+
+ if (mixer->media_mixer_ctl)
+ continue;
+
+ /* allocate media_mixer_ctl */
+ mctl = kzalloc(sizeof(*mctl), GFP_KERNEL);
+ if (!mctl)
+ return -ENOMEM;
+
+ mctl->media_dev = mdev;
+ mctl->media_entity.function = MEDIA_ENT_F_AUDIO_MIXER;
+ mctl->media_entity.name = chip->card->mixername;
+ mctl->media_pad[0].flags = MEDIA_PAD_FL_SINK;
+ mctl->media_pad[1].flags = MEDIA_PAD_FL_SOURCE;
+ mctl->media_pad[2].flags = MEDIA_PAD_FL_SOURCE;
+ media_entity_pads_init(&mctl->media_entity, MEDIA_MIXER_PAD_MAX,
+ mctl->media_pad);
+ ret = media_device_register_entity(mctl->media_dev,
+ &mctl->media_entity);
+ if (ret) {
+ kfree(mctl);
+ return ret;
+ }
+
+ mctl->intf_link = media_create_intf_link(&mctl->media_entity,
+ &ctl_intf->intf,
+ MEDIA_LNK_FL_ENABLED);
+ if (!mctl->intf_link) {
+ media_device_unregister_entity(&mctl->media_entity);
+ media_entity_cleanup(&mctl->media_entity);
+ kfree(mctl);
+ return -ENOMEM;
+ }
+ mctl->intf_devnode = ctl_intf;
+ mixer->media_mixer_ctl = mctl;
+ }
+ return 0;
+}
+
+static void media_snd_mixer_delete(struct snd_usb_audio *chip)
+{
+ struct usb_mixer_interface *mixer;
+ struct media_device *mdev = chip->media_dev;
+
+ if (!mdev)
+ return;
+
+ list_for_each_entry(mixer, &chip->mixer_list, list) {
+ struct media_mixer_ctl *mctl;
+
+ mctl = mixer->media_mixer_ctl;
+ if (!mixer->media_mixer_ctl)
+ continue;
+
+ if (media_devnode_is_registered(mdev->devnode)) {
+ media_device_unregister_entity(&mctl->media_entity);
+ media_entity_cleanup(&mctl->media_entity);
+ }
+ kfree(mctl);
+ mixer->media_mixer_ctl = NULL;
+ }
+ if (media_devnode_is_registered(mdev->devnode))
+ media_devnode_remove(chip->ctl_intf_media_devnode);
+ chip->ctl_intf_media_devnode = NULL;
+}
+
+int media_snd_device_create(struct snd_usb_audio *chip,
+ struct usb_interface *iface)
+{
+ struct media_device *mdev;
+ struct usb_device *usbdev = interface_to_usbdev(iface);
+ int ret;
+
+ /* usb-audio driver is probed for each usb interface, and
+ * there are multiple interfaces per device. Avoid calling
+ * media_device_usb_allocate() each time usb_audio_probe()
+ * is called. Do it only once.
+ */
+ if (chip->media_dev)
+ goto snd_mixer_init;
+
+ mdev = media_device_usb_allocate(usbdev, KBUILD_MODNAME);
+ if (!mdev)
+ return -ENOMEM;
+
+ if (!media_devnode_is_registered(mdev->devnode)) {
+ /* register media_device */
+ ret = media_device_register(mdev);
+ if (ret) {
+ media_device_delete(mdev, KBUILD_MODNAME);
+ dev_err(&usbdev->dev,
+ "Couldn't register media device. Error: %d\n",
+ ret);
+ return ret;
+ }
+ }
+
+ /* save media device - avoid lookups */
+ chip->media_dev = mdev;
+
+snd_mixer_init:
+ /* Create media entities for mixer and control dev */
+ ret = media_snd_mixer_init(chip);
+ if (ret) {
+ dev_err(&usbdev->dev,
+ "Couldn't create media mixer entities. Error: %d\n",
+ ret);
+
+ /* clear saved media_dev */
+ chip->media_dev = NULL;
+
+ return ret;
+ }
+ return 0;
+}
+
+void media_snd_device_delete(struct snd_usb_audio *chip)
+{
+ struct media_device *mdev = chip->media_dev;
+ struct snd_usb_stream *stream;
+
+ /* release resources */
+ list_for_each_entry(stream, &chip->pcm_list, list) {
+ media_snd_stream_delete(&stream->substream[0]);
+ media_snd_stream_delete(&stream->substream[1]);
+ }
+
+ media_snd_mixer_delete(chip);
+
+ if (mdev) {
+ media_device_delete(mdev, KBUILD_MODNAME);
+ chip->media_dev = NULL;
+ }
+}
diff --git a/sound/usb/media.h b/sound/usb/media.h
new file mode 100644
index 0000000..d204375
--- /dev/null
+++ b/sound/usb/media.h
@@ -0,0 +1,73 @@
+/*
+ * media.h - Media Controller specific ALSA driver code
+ *
+ * Copyright (c) 2016 Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
+ * Copyright (c) 2016 Samsung Electronics Co., Ltd.
+ *
+ * This file is released under the GPLv2.
+ */
+
+/*
+ * This file adds Media Controller support to ALSA driver
+ * to use the Media Controller API to share tuner with DVB
+ * and V4L2 drivers that control media device. Media device
+ * is created based on existing quirks framework. Using this
+ * approach, the media controller API usage can be added for
+ * a specific device.
+ */
+#ifndef __MEDIA_H
+
+#ifdef CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER
+
+#include <media/media-device.h>
+#include <media/media-entity.h>
+#include <media/media-dev-allocator.h>
+#include <sound/asound.h>
+
+struct media_ctl {
+ struct media_device *media_dev;
+ struct media_entity media_entity;
+ struct media_intf_devnode *intf_devnode;
+ struct media_link *intf_link;
+ struct media_pad media_pad;
+ struct media_pipeline media_pipe;
+};
+
+/*
+ * One source pad each for SNDRV_PCM_STREAM_CAPTURE and
+ * SNDRV_PCM_STREAM_PLAYBACK. One for sink pad to link
+ * to AUDIO Source
+ */
+#define MEDIA_MIXER_PAD_MAX (SNDRV_PCM_STREAM_LAST + 2)
+
+struct media_mixer_ctl {
+ struct media_device *media_dev;
+ struct media_entity media_entity;
+ struct media_intf_devnode *intf_devnode;
+ struct media_link *intf_link;
+ struct media_pad media_pad[MEDIA_MIXER_PAD_MAX];
+ struct media_pipeline media_pipe;
+};
+
+int media_snd_device_create(struct snd_usb_audio *chip,
+ struct usb_interface *iface);
+void media_snd_device_delete(struct snd_usb_audio *chip);
+int media_snd_stream_init(struct snd_usb_substream *subs, struct snd_pcm *pcm,
+ int stream);
+void media_snd_stream_delete(struct snd_usb_substream *subs);
+int media_snd_start_pipeline(struct snd_usb_substream *subs);
+void media_snd_stop_pipeline(struct snd_usb_substream *subs);
+#else
+static inline int media_snd_device_create(struct snd_usb_audio *chip,
+ struct usb_interface *iface)
+ { return 0; }
+static inline void media_snd_device_delete(struct snd_usb_audio *chip) { }
+static inline int media_snd_stream_init(struct snd_usb_substream *subs,
+ struct snd_pcm *pcm, int stream)
+ { return 0; }
+static inline void media_snd_stream_delete(struct snd_usb_substream *subs) { }
+static inline int media_snd_start_pipeline(struct snd_usb_substream *subs)
+ { return 0; }
+static inline void media_snd_stop_pipeline(struct snd_usb_substream *subs) { }
+#endif
+#endif /* __MEDIA_H */
diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index 3417ef3..f378944 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -3,6 +3,8 @@

#include <sound/info.h>

+struct media_mixer_ctl;
+
struct usb_mixer_interface {
struct snd_usb_audio *chip;
struct usb_host_interface *hostif;
@@ -22,6 +24,7 @@ struct usb_mixer_interface {
struct urb *rc_urb;
struct usb_ctrlrequest *rc_setup_packet;
u8 rc_buffer[6];
+ struct media_mixer_ctl *media_mixer_ctl;
};

#define MAX_CHANNELS 16 /* max logical channels */
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 44d178e..2230865 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -35,6 +35,7 @@
#include "pcm.h"
#include "clock.h"
#include "power.h"
+#include "media.h"

#define SUBSTREAM_FLAG_DATA_EP_STARTED 0
#define SUBSTREAM_FLAG_SYNC_EP_STARTED 1
@@ -717,10 +718,14 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
struct audioformat *fmt;
int ret;

+ ret = media_snd_start_pipeline(subs);
+ if (ret)
+ return ret;
+
ret = snd_pcm_lib_alloc_vmalloc_buffer(substream,
params_buffer_bytes(hw_params));
if (ret < 0)
- return ret;
+ goto err_ret;

subs->pcm_format = params_format(hw_params);
subs->period_bytes = params_period_bytes(hw_params);
@@ -734,22 +739,27 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
dev_dbg(&subs->dev->dev,
"cannot set format: format = %#x, rate = %d, channels = %d\n",
subs->pcm_format, subs->cur_rate, subs->channels);
- return -EINVAL;
+ ret = -EINVAL;
+ goto err_ret;
}

ret = snd_usb_lock_shutdown(subs->stream->chip);
if (ret < 0)
- return ret;
+ goto err_ret;
ret = set_format(subs, fmt);
snd_usb_unlock_shutdown(subs->stream->chip);
if (ret < 0)
- return ret;
+ goto err_ret;

subs->interface = fmt->iface;
subs->altset_idx = fmt->altset_idx;
subs->need_setup_ep = true;

return 0;
+
+err_ret:
+ media_snd_stop_pipeline(subs);
+ return ret;
}

/*
@@ -761,6 +771,7 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
{
struct snd_usb_substream *subs = substream->runtime->private_data;

+ media_snd_stop_pipeline(subs);
subs->cur_audiofmt = NULL;
subs->cur_rate = 0;
subs->period_bytes = 0;
@@ -1221,6 +1232,7 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
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];
+ int ret;

subs->interface = -1;
subs->altset_idx = 0;
@@ -1234,7 +1246,13 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
subs->dsd_dop.channel = 0;
subs->dsd_dop.marker = 1;

- return setup_hw_info(runtime, subs);
+ ret = setup_hw_info(runtime, subs);
+ if (ret == 0) {
+ ret = media_snd_stream_init(subs, as->pcm, direction);
+ if (ret)
+ snd_usb_autosuspend(subs->stream->chip);
+ }
+ return ret;
}

static int snd_usb_pcm_close(struct snd_pcm_substream *substream, int direction)
@@ -1243,6 +1261,7 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream, int direction)
struct snd_usb_substream *subs = &as->substream[direction];

stop_endpoints(subs, true);
+ media_snd_stop_pipeline(subs);

if (subs->interface >= 0 &&
!snd_usb_lock_shutdown(subs->stream->chip)) {
diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index 8a59d47..164e249 100644
--- a/sound/usb/quirks-table.h
+++ b/sound/usb/quirks-table.h
@@ -2886,6 +2886,7 @@ YAMAHA_DEVICE(0x7010, "UB99"),
.product_name = pname, \
.ifnum = QUIRK_ANY_INTERFACE, \
.type = QUIRK_AUDIO_ALIGN_TRANSFER, \
+ .media_device = 1, \
} \
}

diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 8e9548bc..6fe7f21 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -36,6 +36,7 @@
#include "format.h"
#include "clock.h"
#include "stream.h"
+#include "media.h"

/*
* free a substream
@@ -52,6 +53,7 @@ static void free_substream(struct snd_usb_substream *subs)
kfree(fp);
}
kfree(subs->rate_list.list);
+ media_snd_stream_delete(subs);
}


diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index 4d5c89a..89b6853 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -30,6 +30,9 @@
*
*/

+struct media_device;
+struct media_intf_devnode;
+
struct snd_usb_audio {
int index;
struct usb_device *dev;
@@ -61,6 +64,8 @@ struct snd_usb_audio {
bool autoclock; /* from the 'autoclock' module param */

struct usb_host_interface *ctrl_intf; /* the audio control interface */
+ struct media_device *media_dev;
+ struct media_intf_devnode *ctl_intf_media_devnode;
};

#define usb_audio_err(chip, fmt, args...) \
@@ -111,6 +116,7 @@ struct snd_usb_audio_quirk {
const char *product_name;
int16_t ifnum;
uint16_t type;
+ bool media_device;
const void *data;
};

--
2.7.4