Media Device Allocator API

From: Shuah Khan <[email protected]>

Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.

Quoted 7 lines · On Thu 2018-11-01 18:31:30, [email protected] wrote:

From: Shuah Khan <[email protected]>

Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.

Sounds like a ... bad idea?

That's what new "media control" framework is for, no?

Why do you need this?
Pavel

Quoted 9 lines · Pavel Machek

Quoted 7 lines · On Thu 2018-11-01 18:31:30, [email protected] wrote:

From: Shuah Khan <[email protected]>

Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.

Quoted 5 lines

Sounds like a ... bad idea?

That's what new "media control" framework is for, no?

Why do you need this?

Media control framework doesn't address this problem of ownership of the media device when non-media drivers have to own the pipeline. In this case, snd-usb owns the audio pipeline when an audio application is using the device. Without this work, media drivers won't be able to tell if snd-usb is using the tuner and owns the media pipeline.

I am going to clarify this in the commit log.

Quoted 22 lines · Pavel Machek

Quoted 9 lines · On Thu 2018-11-01 18:31:30, [email protected] wrote:

Quoted 7 lines

From: Shuah Khan <[email protected]>

Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.

Quoted 5 lines

Sounds like a ... bad idea?

That's what new "media control" framework is for, no?

Why do you need this?

Media control framework doesn't address this problem of ownership of the media device when non-media drivers have to own the pipeline. In this case, snd-usb owns the audio pipeline when an audio application is using the device. Without this work, media drivers won't be able to tell if snd-usb is using the tuner and owns the media pipeline.

Quoted 1 line

I am going to clarify this in the commit log.

I guess I'll need the explanation, yes.

How can usb soundcard use the tuner? I thought we'd always have userspace component active and moving data between tuner and usb sound card?

Quoted 23 lines · shuah

Quoted 22 lines · Pavel Machek

Quoted 9 lines · On Thu 2018-11-01 18:31:30, [email protected] wrote:

Quoted 7 lines

From: Shuah Khan <[email protected]>

Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.

Quoted 5 lines

Sounds like a ... bad idea?

That's what new "media control" framework is for, no?

Why do you need this?

Media control framework doesn't address this problem of ownership of the media device when non-media drivers have to own the pipeline. In this case, snd-usb owns the audio pipeline when an audio application is using the device. Without this work, media drivers won't be able to tell if snd-usb is using the tuner and owns the media pipeline.

Quoted 7 lines

Quoted 1 line

I am going to clarify this in the commit log.

I guess I'll need the explanation, yes.

How can usb soundcard use the tuner? I thought we'd always have userspace component active and moving data between tuner and usb sound card?

It sounds that the description of the patch is not 100%, as it seems that you're not seeing the hole picture.

This is designed to solve a very common usecase for media devices where one physical device (an USB stick) provides both audio and video.

From: Shuah Khan <[email protected]>

Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.

Signed-off-by Shuah Khan <[email protected]>

---
 Documentation/media/kapi/mc-core.rst |  37 ++++++++
 drivers/media/Makefile               |   3 +-
 drivers/media/media-dev-allocator.c  | 132 +++++++++++++++++++++++++++
 include/media/media-dev-allocator.h  |  53 +++++++++++
 4 files changed, 224 insertions(+), 1 deletion(-)
 create mode 100644 drivers/media/media-dev-allocator.c
 create mode 100644 include/media/media-dev-allocator.h

Documentation/media/kapi/mc-core.rst +0 -0

index 0c05503eaf1f..d6f409598065 100644

Documentation/media/kapi/mc-core.rst +7 -0

+handled by the kref put handler.
+
+API Definitions
+^^^^^^^^^^^^^^^
+
 .. kernel-doc:: include/media/media-device.h
 
 .. kernel-doc:: include/media/media-devnode.h
 
 .. kernel-doc:: include/media/media-entity.h
+
+.. kernel-doc:: include/media/media-dev-allocator.h

drivers/media/Makefile +0 -0

index 594b462ddf0e..8608f0a41dca 100644

drivers/media/Makefile +0 -0

 #
 # I2C drivers should come before other drivers, otherwise they'll fail

drivers/media/media-dev-allocator.c new file +38 -0

new file mode 100644
index 000000000000..262d1293dc13
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * media-dev-allocator.c - Media Controller Device Allocator API
+ *
+ * Copyright (c) 2018 Shuah Khan <[email protected]>
+ *
+ * Credits: Suggested by Laurent Pinchart <[email protected]>
+ */
+
+/*
+ * This file adds a global refcounted Media Controller Device Instance API.
+ * A system wide global media device list is managed and each media device
+ * includes a kref count. The last put on the media device releases the media
+ * device instance.
+ *
+ */
+
+#include <linux/kref.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include <media/media-device.h>
+
+static LIST_HEAD(media_device_list);
+static DEFINE_MUTEX(media_device_lock);
+
+struct media_device_instance {
+	struct media_device mdev;
+	struct module *owner;
+	struct list_head list;
+	struct kref refcount;
+};
+
+static inline struct media_device_instance *
+to_media_device_instance(struct media_device *mdev)
+{
+	return container_of(mdev, struct media_device_instance, mdev);

drivers/media/media-dev-allocator.c new file +23 -0

+{
+	struct media_device_instance *mdi;
+
+	list_for_each_entry(mdi, &media_device_list, list) {
+		if (mdi->mdev.dev != dev)
+			continue;
+
+		kref_get(&mdi->refcount);
+		/* get module reference for the media_device owner */
+		if (find_module(module_name) != mdi->owner &&
+		    !try_module_get(mdi->owner))
+			dev_err(dev, "%s: try_module_get() error\n", __func__);
+		dev_dbg(dev, "%s: get mdev=%p module_name %s\n",
+			__func__, &mdi->mdev, module_name);
+		return &mdi->mdev;
+	}
+
+	mdi = kzalloc(sizeof(*mdi), GFP_KERNEL);
+	if (!mdi)
+		return NULL;
+
+	mdi->owner = find_module(module_name);
+	kref_init(&mdi->refcount);

drivers/media/media-dev-allocator.c new file +38 -0

+{
+	struct media_device *mdev;
+
+	mutex_lock(&media_device_lock);
+	mdev = __media_device_get(&udev->dev, module_name);
+	if (!mdev) {
+		mutex_unlock(&media_device_lock);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* check if media device is already initialized */
+	if (!mdev->dev)
+		__media_device_usb_init(mdev, udev, udev->product,
+					module_name);
+	mutex_unlock(&media_device_lock);
+	return mdev;
+}
+EXPORT_SYMBOL_GPL(media_device_usb_allocate);
+#endif
+
+void media_device_delete(struct media_device *mdev, char *module_name)
+{
+	struct media_device_instance *mdi = to_media_device_instance(mdev);
+
+	dev_dbg(mdi->mdev.dev, "%s: mdev=%p module_name %s\n",
+		__func__, &mdi->mdev, module_name);
+
+	mutex_lock(&media_device_lock);
+	/* put module reference if media_device owner is not THIS_MODULE */
+	if (mdi->owner != find_module(module_name)) {
+		module_put(mdi->owner);
+		dev_dbg(mdi->mdev.dev,
+			"%s decremented owner module reference\n", __func__);
+	}
+	mutex_unlock(&media_device_lock);
+	kref_put(&mdi->refcount, media_device_instance_release);
+}
+EXPORT_SYMBOL_GPL(media_device_delete);

include/media/media-dev-allocator.h new file +12 -0

new file mode 100644
index 000000000000..8fbadff2cef8
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * media-dev-allocator.h - Media Controller Device Allocator API
+ *
+ * Copyright (c) 2018 Shuah Khan <[email protected]>
+ *
+ * Credits: Suggested by Laurent Pinchart <[email protected]>
+ */
+
+/*
+ * This file adds a global ref-counted Media Controller Device Instance API.
+ * A system wide global media device list is managed and each media device

include/media/media-dev-allocator.h new file +21 -0

+/**
+ * media_device_usb_allocate() - Allocate and return struct &media device
+ *
+ * @udev:		struct &usb_device pointer
+ * @module_name:	should be filled with %KBUILD_MODNAME
+ *
+ * This interface should be called to allocate a Media Device when multiple
+ * drivers share usb_device and the media device. This interface allocates
+ * &media_device structure and calls media_device_usb_init() to initialize
+ * it.
+ *
+ */
+struct media_device *media_device_usb_allocate(struct usb_device *udev,
+					       char *module_name);
+/**
+ * media_device_delete() - Release media device. Calls kref_put().
+ *
+ * @mdev:		struct &media_device pointer
+ * @module_name:	should be filled with %KBUILD_MODNAME
+ *
+ * This interface should be called to put Media Device Instance kref.

Quoted 9 lines · On 11/02/2018 01:31 AM, [email protected] wrote:

From: Shuah Khan <[email protected]>

Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released.

Signed-off-by Shuah Khan <[email protected]>

Quoted 14 lines

---
  Documentation/media/kapi/mc-core.rst |  37 ++++++++
  drivers/media/Makefile               |   3 +-
  drivers/media/media-dev-allocator.c  | 132 +++++++++++++++++++++++++++
  include/media/media-dev-allocator.h  |  53 +++++++++++
  4 files changed, 224 insertions(+), 1 deletion(-)

create mode 100644 drivers/media/media-dev-allocator.c create mode 100644 include/media/media-dev-allocator.h

Documentation/media/kapi/mc-core.rst +0 -0

index 0c05503eaf1f..d6f409598065 100644

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 263

Quoted 7 lines

Documentation/media/kapi/mc-core.rst +4 -0

@@ -257,8 +257,45 @@ Subsystems should facilitate link validation by providing subsystem specific
  helper functions to provide easy access for commonly needed information, and
  in the end provide a way to use driver-specific callbacks.
 
+Media Controller Device Allocator API
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When media device belongs to more than one driver, the shared media device

When -> When the

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 266

Quoted 3 lines

Documentation/media/kapi/mc-core.rst +3 -0

+is allocated with the shared struct device as the key for look ups.
+
+Shared media device should stay in registered state until the last driver

Shared -> The shared

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 267

Quoted 1 line

Documentation/media/kapi/mc-core.rst +1 -0

+unregisters it. In addition, media device should be released when all the

media -> the media

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 270

Quoted 3 lines

Documentation/media/kapi/mc-core.rst +3 -0

+references are released. Each driver gets a reference to the media device
+during probe, when it allocates the media device. If media device is already
+allocated, allocate API bumps up the refcount and return the existing media

allocate -> the allocate
return -> returns

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 271

Quoted 1 line

Documentation/media/kapi/mc-core.rst +1 -0

+device. Driver puts the reference back from its disconnect routine when it

Driver -> The driver
from -> in

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 274

Quoted 3 lines

Documentation/media/kapi/mc-core.rst +3 -0

+calls :c:func:`media_device_delete()`.
+
+Media device is unregistered and cleaned up from the kref put handler to

Media -> The media
from -> in

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 276

Quoted 2 lines

Documentation/media/kapi/mc-core.rst +2 -0

+ensure that the media device stays in registered state until the last driver
+unregisters the media device.

What happens if an application still has the media device open and you forcibly remove the last driver? I think it should be OK since the media_devnode struct isn't freed until the last open filehandle closes. But it is good to test this.

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 280

Quoted 4 lines

Documentation/media/kapi/mc-core.rst +4 -0

+
+**Driver Usage**
+
+Drivers should use the media-core routines to get register reference and

'get register reference'? Not sure what you meant to say.

Documentation/media/kapi/mc-core.rst Subsystems should facilitate link validation by providing subsystem specific · line 289

Quoted 9 lines

Documentation/media/kapi/mc-core.rst +9 -0

+call :c:func:`media_device_delete()` routine to make sure the shared media
+device delete is handled correctly.
+
+**driver probe:**
+Call :c:func:`media_device_usb_allocate()` to allocate or get a reference
+Call :c:func:`media_device_register()`, if media devnode isn't registered
+
+**driver disconnect:**
+Call :c:func:`media_device_delete()` to free the media_device. Free'ing is

Free'ing -> Freeing

Quoted 17 lines

Documentation/media/kapi/mc-core.rst +7 -0

+handled by the kref put handler.
+
+API Definitions
+^^^^^^^^^^^^^^^
+
  .. kernel-doc:: include/media/media-device.h
 
  .. kernel-doc:: include/media/media-devnode.h
 
  .. kernel-doc:: include/media/media-entity.h
+
+.. kernel-doc:: include/media/media-dev-allocator.h

drivers/media/Makefile +0 -0

index 594b462ddf0e..8608f0a41dca 100644

drivers/media/Makefile line 7

Quoted 6 lines

drivers/media/Makefile +2 -1

@@ -3,7 +3,8 @@
  # Makefile for the kernel multimedia device drivers.
  #
 
-media-objs	:= media-device.o media-devnode.o media-entity.o
+media-objs	:= media-device.o media-devnode.o media-entity.o \
+		   media-dev-allocator.o

Perhaps only add media-dev-allocator if CONFIG_USB is enabled?

Quoted 51 lines

drivers/media/Makefile +0 -0

  #
  # I2C drivers should come before other drivers, otherwise they'll fail

drivers/media/media-dev-allocator.c new file +42 -0

new file mode 100644
index 000000000000..262d1293dc13
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * media-dev-allocator.c - Media Controller Device Allocator API
+ *
+ * Copyright (c) 2018 Shuah Khan <[email protected]>
+ *
+ * Credits: Suggested by Laurent Pinchart <[email protected]>
+ */
+
+/*
+ * This file adds a global refcounted Media Controller Device Instance API.
+ * A system wide global media device list is managed and each media device
+ * includes a kref count. The last put on the media device releases the media
+ * device instance.
+ *
+ */
+
+#include <linux/kref.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include <media/media-device.h>
+
+static LIST_HEAD(media_device_list);
+static DEFINE_MUTEX(media_device_lock);
+
+struct media_device_instance {
+	struct media_device mdev;
+	struct module *owner;
+	struct list_head list;
+	struct kref refcount;
+};
+
+static inline struct media_device_instance *
+to_media_device_instance(struct media_device *mdev)
+{
+	return container_of(mdev, struct media_device_instance, mdev);
+}
+
+static void media_device_instance_release(struct kref *kref)
+{

drivers/media/media-dev-allocator.c line 48

Quoted 6 lines

drivers/media/media-dev-allocator.c new file +6 -0

+	struct media_device_instance *mdi =
+		container_of(kref, struct media_device_instance, refcount);
+
+	dev_dbg(mdi->mdev.dev, "%s: mdev=%p\n", __func__, &mdi->mdev);
+
+	mutex_lock(&media_device_lock);

Can't the lock be moved down to just before list_del? Or am I missing something?

Quoted 7 lines

drivers/media/media-dev-allocator.c new file +7 -0

+
+	media_device_unregister(&mdi->mdev);
+	media_device_cleanup(&mdi->mdev);
+
+	list_del(&mdi->list);
+	mutex_unlock(&media_device_lock);
+

drivers/media/media-dev-allocator.c line 61

Quoted 6 lines

drivers/media/media-dev-allocator.c new file +6 -0

+	kfree(mdi);
+}
+
+/* Callers should hold media_device_lock when calling this function */
+static struct media_device *__media_device_get(struct device *dev,
+					       char *module_name)

const char *

From: Shuah Khan <[email protected]>

Move ALSA MEDIA_INTF_T* interface types back into __KERNEL__ scope to get ready for adding ALSA support to the media controller.

Signed-off-by Shuah Khan <[email protected]>

---
 include/uapi/linux/media.h | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

include/uapi/linux/media.h +0 -0

index 36f76e777ef9..07be07263597 100644
@@ -262,6 +262,16 @@ struct media_links_enum {
 #define MEDIA_INTF_T_V4L_SWRADIO		(MEDIA_INTF_T_V4L_BASE + 4)
 #define MEDIA_INTF_T_V4L_TOUCH			(MEDIA_INTF_T_V4L_BASE + 5)
 

include/uapi/linux/media.h +0 -15

 #if defined(__KERNEL__)
 
 /*

@@ -404,21 +414,6 @@ struct media_v2_topology {
 
 #define MEDIA_ENT_F_DTV_DECODER			MEDIA_ENT_F_DV_DECODER
 
-/*
- * There is still no ALSA support in the media controller. These
- * defines should not have been added and we leave them here only
- * in case some application tries to use these defines.
- */
-#define MEDIA_INTF_T_ALSA_BASE			0x00000300
-#define MEDIA_INTF_T_ALSA_PCM_CAPTURE		(MEDIA_INTF_T_ALSA_BASE)
-#define MEDIA_INTF_T_ALSA_PCM_PLAYBACK		(MEDIA_INTF_T_ALSA_BASE + 1)
-#define MEDIA_INTF_T_ALSA_CONTROL		(MEDIA_INTF_T_ALSA_BASE + 2)
-#define MEDIA_INTF_T_ALSA_COMPRESS		(MEDIA_INTF_T_ALSA_BASE + 3)
-#define MEDIA_INTF_T_ALSA_RAWMIDI		(MEDIA_INTF_T_ALSA_BASE + 4)
-#define MEDIA_INTF_T_ALSA_HWDEP			(MEDIA_INTF_T_ALSA_BASE + 5)
-#define MEDIA_INTF_T_ALSA_SEQUENCER		(MEDIA_INTF_T_ALSA_BASE + 6)
-#define MEDIA_INTF_T_ALSA_TIMER			(MEDIA_INTF_T_ALSA_BASE + 7)
-
 /* Obsolete symbol for media_version, no longer used in the kernel */
 #define MEDIA_API_VERSION			((0 << 16) | (1 << 8) | 0)
 

Quoted 18 lines · On 11/02/2018 01:31 AM, [email protected] wrote:

From: Shuah Khan <[email protected]>

Move ALSA MEDIA_INTF_T* interface types back into __KERNEL__ scope to get ready for adding ALSA support to the media controller.

Signed-off-by Shuah Khan <[email protected]>

---
  include/uapi/linux/media.h | 25 ++++++++++---------------
  1 file changed, 10 insertions(+), 15 deletions(-)

include/uapi/linux/media.h +0 -0

index 36f76e777ef9..07be07263597 100644
@@ -262,6 +262,16 @@ struct media_links_enum {
  #define MEDIA_INTF_T_V4L_SWRADIO		(MEDIA_INTF_T_V4L_BASE + 4)
  #define MEDIA_INTF_T_V4L_TOUCH			(MEDIA_INTF_T_V4L_BASE + 5)
 

include/uapi/linux/media.h struct media_links_enum { · line 274

Quoted 10 lines

include/uapi/linux/media.h +10 -0

+#define MEDIA_INTF_T_ALSA_BASE			0x00000300
+#define MEDIA_INTF_T_ALSA_PCM_CAPTURE		(MEDIA_INTF_T_ALSA_BASE)
+#define MEDIA_INTF_T_ALSA_PCM_PLAYBACK		(MEDIA_INTF_T_ALSA_BASE + 1)
+#define MEDIA_INTF_T_ALSA_CONTROL		(MEDIA_INTF_T_ALSA_BASE + 2)
+#define MEDIA_INTF_T_ALSA_COMPRESS		(MEDIA_INTF_T_ALSA_BASE + 3)
+#define MEDIA_INTF_T_ALSA_RAWMIDI		(MEDIA_INTF_T_ALSA_BASE + 4)
+#define MEDIA_INTF_T_ALSA_HWDEP			(MEDIA_INTF_T_ALSA_BASE + 5)
+#define MEDIA_INTF_T_ALSA_SEQUENCER		(MEDIA_INTF_T_ALSA_BASE + 6)
+#define MEDIA_INTF_T_ALSA_TIMER			(MEDIA_INTF_T_ALSA_BASE + 7)
+

I would only enable those defines that you need for the next patch.

From: Shuah Khan <[email protected]>

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 <[email protected]>

---
 sound/usb/Kconfig        |   4 +
 sound/usb/Makefile       |   2 +
 sound/usb/card.c         |  14 ++
 sound/usb/card.h         |   3 +
 sound/usb/media.c        | 320 +++++++++++++++++++++++++++++++++++++++
 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(+), 4 deletions(-)
 create mode 100644 sound/usb/media.c
 create mode 100644 sound/usb/media.h

sound/usb/Kconfig +4 -0

index f61b5662bb89..6319b544ba3a 100644
@@ -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

sound/usb/Makefile +2 -0

index d330f74c90e6..e1ce257ab705 100644
@@ -18,6 +18,8 @@ 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

sound/usb/card.c +1 -0

index 2bfe4e80a6b9..d9ae331280a2 100644
@@ -68,6 +68,7 @@
 #include "format.h"
 #include "power.h"
 #include "stream.h"
+#include "media.h"
 
 MODULE_AUTHOR("Takashi Iwai <[email protected]>");
 MODULE_DESCRIPTION("USB Audio");

sound/usb/card.c +2 -0

+	}
+
 	usb_chip[chip->index] = chip;
 	chip->num_interfaces++;
 	usb_set_intfdata(intf, chip);

sound/usb/card.c +3 -0

+		 */
+		media_snd_device_delete(chip);
+
 		/* release mixer resources */
 		list_for_each_entry(mixer, &chip->mixer_list, list) {
 			snd_usb_mixer_disconnect(mixer);

sound/usb/card.h +3 -0

index ac785d15ced4..5dd3538ed6b5 100644
@@ -108,6 +108,8 @@ struct snd_usb_endpoint {
 	struct list_head list;
 };
 
+struct media_ctl;
+
 struct snd_usb_substream {
 	struct snd_usb_stream *stream;
 	struct usb_device *dev;

@@ -160,6 +162,7 @@ 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 {

sound/usb/media.c new file +0 -0

new file mode 100644
index 000000000000..140a98eed294

sound/usb/media.c new file +9 -0

+ * 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>

sound/usb/media.c new file +232 -0

+			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.
+	 */

sound/usb/media.c new file +46 -0

+		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;
+	}
+}

sound/usb/media.h new file +73 -0

new file mode 100644
index 000000000000..fbefa9cad215
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * media.h - Media Controller specific ALSA driver code
+ *
+ * Copyright (c) 2018 Shuah Khan <[email protected]>
+ *
+ */
+
+/*
+ * 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 <linux/media.h>
+#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 */

sound/usb/mixer.h +3 -0

index 3d12af8bf191..394cd9107507 100644
@@ -4,6 +4,8 @@
 
 #include <sound/info.h>
 
+struct media_mixer_ctl;
+
 struct usb_mixer_interface {
 	struct snd_usb_audio *chip;
 	struct usb_host_interface *hostif;

@@ -23,6 +25,7 @@ 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;
 
 	bool disconnected;
 };

sound/usb/pcm.c +25 -4

index 382847154227..a1971a87c613 100644
@@ -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

@@ -776,6 +777,10 @@ 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;
+
 	if (snd_usb_use_vmalloc)
 		ret = snd_pcm_lib_alloc_vmalloc_buffer(substream,
 						       params_buffer_bytes(hw_params));

@@ -783,7 +788,7 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 		ret = snd_pcm_lib_malloc_pages(substream,
 					       params_buffer_bytes(hw_params));
 	if (ret < 0)
-		return ret;
+		goto stop_pipeline;
 
 	subs->pcm_format = params_format(hw_params);
 	subs->period_bytes = params_period_bytes(hw_params);

@@ -797,12 +802,13 @@ 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 stop_pipeline;
 	}
 
 	ret = snd_usb_lock_shutdown(subs->stream->chip);
 	if (ret < 0)
-		return ret;
+		goto stop_pipeline;
 
 	ret = snd_usb_pcm_change_state(subs, UAC3_PD_STATE_D0);
 	if (ret < 0)

@@ -818,6 +824,12 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 
  unlock:
 	snd_usb_unlock_shutdown(subs->stream->chip);
+	if (ret < 0)
+		goto stop_pipeline;
+	return ret;
+
+ stop_pipeline:
+	media_snd_stop_pipeline(subs);
 	return ret;
 }
 

@@ -830,6 +842,7 @@ 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;

@@ -1302,6 +1315,7 @@ 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];
+	int ret;
 
 	subs->interface = -1;
 	subs->altset_idx = 0;

@@ -1315,7 +1329,13 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream)
 	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)

@@ -1326,6 +1346,7 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream)
 	int ret;
 
 	stop_endpoints(subs, true);
+	media_snd_stop_pipeline(subs);
 
 	if (!as->chip->keep_iface &&
 	    subs->interface >= 0 &&

sound/usb/quirks-table.h +1 -0

index 08aa78007020..02789d1b2fec 100644
@@ -2887,6 +2887,7 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 		.product_name = pname, \
 		.ifnum = QUIRK_ANY_INTERFACE, \
 		.type = QUIRK_AUDIO_ALIGN_TRANSFER, \
+		.media_device = 1, \
 	} \
 }
 

sound/usb/stream.c +2 -0

index 67cf849aa16b..5439dd2e6980 100644
@@ -38,6 +38,7 @@
 #include "clock.h"
 #include "stream.h"
 #include "power.h"
+#include "media.h"
 
 /*
  * free a substream

@@ -55,6 +56,7 @@ static void free_substream(struct snd_usb_substream *subs)
 	}
 	kfree(subs->rate_list.list);
 	kfree(subs->str_pd);
+	media_snd_stream_delete(subs);
 }
 
 

sound/usb/usbaudio.h +5 -0

index b9faeca645fd..72bdae5ca54a 100644
@@ -30,6 +30,9 @@
  *
  */
 
+struct media_device;
+struct media_intf_devnode;
+
 struct snd_usb_audio {
 	int index;
 	struct usb_device *dev;

@@ -66,6 +69,8 @@ struct snd_usb_audio {
 					 */
 
 	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...) \

Quoted 9 lines · On 11/02/2018 01:31 AM, [email protected] wrote:

From: Shuah Khan <[email protected]>

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.

Quoted 8 lines

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 <[email protected]>