diff mbox series

[v9,4/4] sound/usb: Use Media Controller API to share media resources

Message ID 2fb40852e4035b2a58010ce7416448918f12804f.1545154778.git.shuah@kernel.org (mailing list archive)
State New, archived
Headers show
Series Media Device Allocator API | expand

Commit Message

Shuah Dec. 18, 2018, 5:59 p.m. UTC
From: Shuah Khan <shuah@kernel.org>

Media Device Allocator API to allows multiple drivers share a media device.
This API solves a very common use-case for media devices where one physical
device (an USB stick) provides both audio and video. When such media device
exposes a standard USB Audio class, a proprietary Video class, two or more
independent drivers will share a single physical USB bridge. In such cases,
it is necessary to coordinate access to the shared resource.

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.

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

The 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 <shuah@kernel.org>
---
 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        |  74 +++++++++
 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, 455 insertions(+), 4 deletions(-)
 create mode 100644 sound/usb/media.c
 create mode 100644 sound/usb/media.h

Comments

Takashi Iwai Dec. 19, 2018, 1:51 p.m. UTC | #1
On Tue, 18 Dec 2018 18:59:39 +0100,
shuah@kernel.org wrote:
> 
> From: Shuah Khan <shuah@kernel.org>
> 
> Media Device Allocator API to allows multiple drivers share a media device.
> This API solves a very common use-case for media devices where one physical
> device (an USB stick) provides both audio and video. When such media device
> exposes a standard USB Audio class, a proprietary Video class, two or more
> independent drivers will share a single physical USB bridge. In such cases,
> it is necessary to coordinate access to the shared resource.
> 
> 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.
> 
> Change the ALSA driver to use the Media Controller API to share media
> resources with DVB, and V4L2 drivers on a AU0828 media device.
> 
> The 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 <shuah@kernel.org>

Feel free to take my ack regarding the sound stuff:
  Reviewed-by: Takashi Iwai <tiwai@suse.de>


Thanks!

Takashi
Shuah Jan. 11, 2019, 2:57 p.m. UTC | #2
On 12/19/18 6:51 AM, Takashi Iwai wrote:
> On Tue, 18 Dec 2018 18:59:39 +0100,
> shuah@kernel.org wrote:
>>
>> From: Shuah Khan <shuah@kernel.org>
>>
>> Media Device Allocator API to allows multiple drivers share a media device.
>> This API solves a very common use-case for media devices where one physical
>> device (an USB stick) provides both audio and video. When such media device
>> exposes a standard USB Audio class, a proprietary Video class, two or more
>> independent drivers will share a single physical USB bridge. In such cases,
>> it is necessary to coordinate access to the shared resource.
>>
>> 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.
>>
>> Change the ALSA driver to use the Media Controller API to share media
>> resources with DVB, and V4L2 drivers on a AU0828 media device.
>>
>> The 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 <shuah@kernel.org>
> 
> Feel free to take my ack regarding the sound stuff:
>    Reviewed-by: Takashi Iwai <tiwai@suse.de>
> 
> 
> Thanks!
> 
> Takashi
> 

Hi Mauro,

Any update on this patch series?

thanks,
-- Shuah
Hans Verkuil Jan. 11, 2019, 2:59 p.m. UTC | #3
On 1/11/19 3:57 PM, shuah wrote:
> On 12/19/18 6:51 AM, Takashi Iwai wrote:
>> On Tue, 18 Dec 2018 18:59:39 +0100,
>> shuah@kernel.org wrote:
>>>
>>> From: Shuah Khan <shuah@kernel.org>
>>>
>>> Media Device Allocator API to allows multiple drivers share a media device.
>>> This API solves a very common use-case for media devices where one physical
>>> device (an USB stick) provides both audio and video. When such media device
>>> exposes a standard USB Audio class, a proprietary Video class, two or more
>>> independent drivers will share a single physical USB bridge. In such cases,
>>> it is necessary to coordinate access to the shared resource.
>>>
>>> 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.
>>>
>>> Change the ALSA driver to use the Media Controller API to share media
>>> resources with DVB, and V4L2 drivers on a AU0828 media device.
>>>
>>> The 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 <shuah@kernel.org>
>>
>> Feel free to take my ack regarding the sound stuff:
>>    Reviewed-by: Takashi Iwai <tiwai@suse.de>
>>
>>
>> Thanks!
>>
>> Takashi
>>
> 
> Hi Mauro,
> 
> Any update on this patch series?

I'm planning to process this series for 5.1. Haven't gotten around to it yet,
but I expect to do this next week.

Still going through all the pending patches after the Christmas period :-)

Regards,

	Hans
Shuah Jan. 11, 2019, 3:04 p.m. UTC | #4
On 1/11/19 7:59 AM, Hans Verkuil wrote:
> On 1/11/19 3:57 PM, shuah wrote:
>> On 12/19/18 6:51 AM, Takashi Iwai wrote:
>>> On Tue, 18 Dec 2018 18:59:39 +0100,
>>> shuah@kernel.org wrote:
>>>>
>>>> From: Shuah Khan <shuah@kernel.org>
>>>>
>>>> Media Device Allocator API to allows multiple drivers share a media device.
>>>> This API solves a very common use-case for media devices where one physical
>>>> device (an USB stick) provides both audio and video. When such media device
>>>> exposes a standard USB Audio class, a proprietary Video class, two or more
>>>> independent drivers will share a single physical USB bridge. In such cases,
>>>> it is necessary to coordinate access to the shared resource.
>>>>
>>>> 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.
>>>>
>>>> Change the ALSA driver to use the Media Controller API to share media
>>>> resources with DVB, and V4L2 drivers on a AU0828 media device.
>>>>
>>>> The 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 <shuah@kernel.org>
>>>
>>> Feel free to take my ack regarding the sound stuff:
>>>     Reviewed-by: Takashi Iwai <tiwai@suse.de>
>>>
>>>
>>> Thanks!
>>>
>>> Takashi
>>>
>>
>> Hi Mauro,
>>
>> Any update on this patch series?
> 
> I'm planning to process this series for 5.1. Haven't gotten around to it yet,
> but I expect to do this next week.
> 
> Still going through all the pending patches after the Christmas period :-)
> 
> Regards,
> 
> 	Hans
> 

Hans,

Thanks for a quick reply. No worries. I am recovering from the Christmas
and vacation myself. :)

thanks,
-- Shuah
Hans Verkuil Jan. 18, 2019, 8:36 a.m. UTC | #5
On 12/18/18 6:59 PM, shuah@kernel.org wrote:
> From: Shuah Khan <shuah@kernel.org>
> 
> Media Device Allocator API to allows multiple drivers share a media device.
> This API solves a very common use-case for media devices where one physical
> device (an USB stick) provides both audio and video. When such media device
> exposes a standard USB Audio class, a proprietary Video class, two or more
> independent drivers will share a single physical USB bridge. In such cases,
> it is necessary to coordinate access to the shared resource.
> 
> 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.
> 
> Change the ALSA driver to use the Media Controller API to share media
> resources with DVB, and V4L2 drivers on a AU0828 media device.
> 
> The 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 <shuah@kernel.org>
> ---
>  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        |  74 +++++++++
>  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, 455 insertions(+), 4 deletions(-)
>  create mode 100644 sound/usb/media.c
>  create mode 100644 sound/usb/media.h
> 

<snip>

> +int snd_media_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)) {

It looks like you missed my comment for v8:

"You should first configure the media device before registering it."

In other words, first create the media entities, and only then do you
register the media device. Otherwise it will come up without any alsa
entities, which are then added. So an application that immediately
opens the media device upon creation will see a topology that is still
in flux.

> +		/* 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 = snd_media_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;
> +}

I'll do some testing of this series on Monday.

Regards,

	Hans
Shuah Jan. 18, 2019, 9:54 p.m. UTC | #6
On 1/18/19 1:36 AM, Hans Verkuil wrote:
> On 12/18/18 6:59 PM, shuah@kernel.org wrote:
>> From: Shuah Khan <shuah@kernel.org>
>>
>> Media Device Allocator API to allows multiple drivers share a media device.
>> This API solves a very common use-case for media devices where one physical
>> device (an USB stick) provides both audio and video. When such media device
>> exposes a standard USB Audio class, a proprietary Video class, two or more
>> independent drivers will share a single physical USB bridge. In such cases,
>> it is necessary to coordinate access to the shared resource.
>>
>> 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.
>>
>> Change the ALSA driver to use the Media Controller API to share media
>> resources with DVB, and V4L2 drivers on a AU0828 media device.
>>
>> The 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 <shuah@kernel.org>
>> ---
>>   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        |  74 +++++++++
>>   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, 455 insertions(+), 4 deletions(-)
>>   create mode 100644 sound/usb/media.c
>>   create mode 100644 sound/usb/media.h
>>
> 
> <snip>
> 
>> +int snd_media_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)) {
> 
> It looks like you missed my comment for v8:
> 
> "You should first configure the media device before registering it."
> 
> In other words, first create the media entities, and only then do you
> register the media device. Otherwise it will come up without any alsa
> entities, which are then added. So an application that immediately
> opens the media device upon creation will see a topology that is still
> in flux.

Yes. You are right. I saw your comment and thought I got it addressed.
I will fix it. I have the logic correct in au0828, but not here.

Thanks,
-- Shuah
Shuah Jan. 19, 2019, 1:03 a.m. UTC | #7
On 1/18/19 2:54 PM, shuah wrote:
> On 1/18/19 1:36 AM, Hans Verkuil wrote:
>> On 12/18/18 6:59 PM, shuah@kernel.org wrote:
>>> From: Shuah Khan <shuah@kernel.org>
>>>
>>> Media Device Allocator API to allows multiple drivers share a media 
>>> device.
>>> This API solves a very common use-case for media devices where one 
>>> physical
>>> device (an USB stick) provides both audio and video. When such media 
>>> device
>>> exposes a standard USB Audio class, a proprietary Video class, two or 
>>> more
>>> independent drivers will share a single physical USB bridge. In such 
>>> cases,
>>> it is necessary to coordinate access to the shared resource.
>>>
>>> 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.
>>>
>>> Change the ALSA driver to use the Media Controller API to share media
>>> resources with DVB, and V4L2 drivers on a AU0828 media device.
>>>
>>> The 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 <shuah@kernel.org>
>>> ---
>>>   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        |  74 +++++++++
>>>   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, 455 insertions(+), 4 deletions(-)
>>>   create mode 100644 sound/usb/media.c
>>>   create mode 100644 sound/usb/media.h
>>>
>>
>> <snip>
>>
>>> +int snd_media_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)) {
>>
>> It looks like you missed my comment for v8:
>>
>> "You should first configure the media device before registering it."
>>
>> In other words, first create the media entities, and only then do you
>> register the media device. Otherwise it will come up without any alsa
>> entities, which are then added. So an application that immediately
>> opens the media device upon creation will see a topology that is still
>> in flux.
> 
> Yes. You are right. I saw your comment and thought I got it addressed.
> I will fix it. I have the logic correct in au0828, but not here.
> 

One thing to mention here is some ALSA entities get created dynamically
during PCM open when stream is initialized. This happens after media
device is registered. These get deleted when pcm close happens. There is
no way to avoid creating entities after media device register.

snd_media_device_create() could get called after media_device_register()
happens, if au0828 registers it first.

I did find a problem in snd_media_device_create() and I will send a v10
with that fix.

thanks,
-- Shuah
Hans Verkuil Jan. 19, 2019, 10:30 a.m. UTC | #8
On 01/19/2019 02:03 AM, shuah wrote:
> On 1/18/19 2:54 PM, shuah wrote:
>> On 1/18/19 1:36 AM, Hans Verkuil wrote:
>>> On 12/18/18 6:59 PM, shuah@kernel.org wrote:
>>>> From: Shuah Khan <shuah@kernel.org>
>>>>
>>>> Media Device Allocator API to allows multiple drivers share a media 
>>>> device.
>>>> This API solves a very common use-case for media devices where one 
>>>> physical
>>>> device (an USB stick) provides both audio and video. When such media 
>>>> device
>>>> exposes a standard USB Audio class, a proprietary Video class, two or 
>>>> more
>>>> independent drivers will share a single physical USB bridge. In such 
>>>> cases,
>>>> it is necessary to coordinate access to the shared resource.
>>>>
>>>> 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.
>>>>
>>>> Change the ALSA driver to use the Media Controller API to share media
>>>> resources with DVB, and V4L2 drivers on a AU0828 media device.
>>>>
>>>> The 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 <shuah@kernel.org>
>>>> ---
>>>>   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        |  74 +++++++++
>>>>   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, 455 insertions(+), 4 deletions(-)
>>>>   create mode 100644 sound/usb/media.c
>>>>   create mode 100644 sound/usb/media.h
>>>>
>>>
>>> <snip>
>>>
>>>> +int snd_media_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)) {
>>>
>>> It looks like you missed my comment for v8:
>>>
>>> "You should first configure the media device before registering it."
>>>
>>> In other words, first create the media entities, and only then do you
>>> register the media device. Otherwise it will come up without any alsa
>>> entities, which are then added. So an application that immediately
>>> opens the media device upon creation will see a topology that is still
>>> in flux.
>>
>> Yes. You are right. I saw your comment and thought I got it addressed.
>> I will fix it. I have the logic correct in au0828, but not here.
>>
> 
> One thing to mention here is some ALSA entities get created dynamically
> during PCM open when stream is initialized. This happens after media
> device is registered. These get deleted when pcm close happens. There is
> no way to avoid creating entities after media device register.

That's OK. We're missing some infrastructure (media events) to inform the
application about topology changes.

But when registering the media device for the first time it is good practice
to do that after creating all the entities that you can.

Regards,

	Hans

> snd_media_device_create() could get called after media_device_register()
> happens, if au0828 registers it first.
> 
> I did find a problem in snd_media_device_create() and I will send a v10
> with that fix.
> 
> thanks,
> -- Shuah
>
Shuah Jan. 20, 2019, 7:32 p.m. UTC | #9
On 1/19/19 3:30 AM, Hans Verkuil wrote:
> On 01/19/2019 02:03 AM, shuah wrote:
>> On 1/18/19 2:54 PM, shuah wrote:
>>> On 1/18/19 1:36 AM, Hans Verkuil wrote:
>>>> On 12/18/18 6:59 PM, shuah@kernel.org wrote:
>>>>> From: Shuah Khan <shuah@kernel.org>
>>>>>
>>>>> Media Device Allocator API to allows multiple drivers share a media
>>>>> device.
>>>>> This API solves a very common use-case for media devices where one
>>>>> physical
>>>>> device (an USB stick) provides both audio and video. When such media
>>>>> device
>>>>> exposes a standard USB Audio class, a proprietary Video class, two or
>>>>> more
>>>>> independent drivers will share a single physical USB bridge. In such
>>>>> cases,
>>>>> it is necessary to coordinate access to the shared resource.
>>>>>
>>>>> 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.
>>>>>
>>>>> Change the ALSA driver to use the Media Controller API to share media
>>>>> resources with DVB, and V4L2 drivers on a AU0828 media device.
>>>>>
>>>>> The 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 <shuah@kernel.org>
>>>>> ---
>>>>>    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        |  74 +++++++++
>>>>>    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, 455 insertions(+), 4 deletions(-)
>>>>>    create mode 100644 sound/usb/media.c
>>>>>    create mode 100644 sound/usb/media.h
>>>>>
>>>>
>>>> <snip>
>>>>
>>>>> +int snd_media_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)) {
>>>>
>>>> It looks like you missed my comment for v8:
>>>>
>>>> "You should first configure the media device before registering it."
>>>>
>>>> In other words, first create the media entities, and only then do you
>>>> register the media device. Otherwise it will come up without any alsa
>>>> entities, which are then added. So an application that immediately
>>>> opens the media device upon creation will see a topology that is still
>>>> in flux.
>>>
>>> Yes. You are right. I saw your comment and thought I got it addressed.
>>> I will fix it. I have the logic correct in au0828, but not here.
>>>
>>
>> One thing to mention here is some ALSA entities get created dynamically
>> during PCM open when stream is initialized. This happens after media
>> device is registered. These get deleted when pcm close happens. There is
>> no way to avoid creating entities after media device register.
> 
> That's OK. We're missing some infrastructure (media events) to inform the
> application about topology changes.
> 
> But when registering the media device for the first time it is good practice
> to do that after creating all the entities that you can.
> 

Great. We have the same understanding. I think at least one mixer
controller entries can be created prior to registering the media
device. I am working on v10 to do that. Sorry I misread init sequence
in this patch the flow the first time around for v9.

thanks,
-- Shuah
diff mbox series

Patch

diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig
index f61b5662bb89..6319b544ba3a 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 d330f74c90e6..e1ce257ab705 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile
@@ -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
diff --git a/sound/usb/card.c b/sound/usb/card.c
index a105947eaf55..4ad075e98dc2 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -68,6 +68,7 @@ 
 #include "format.h"
 #include "power.h"
 #include "stream.h"
+#include "media.h"
 
 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
 MODULE_DESCRIPTION("USB Audio");
@@ -673,6 +674,11 @@  static int usb_audio_probe(struct usb_interface *intf,
 	if (err < 0)
 		goto __error;
 
+	if (quirk && quirk->shares_media_device) {
+		/* don't want to fail when snd_media_device_create() fails */
+		snd_media_device_create(chip, intf);
+	}
+
 	usb_chip[chip->index] = chip;
 	chip->num_interfaces++;
 	usb_set_intfdata(intf, chip);
@@ -732,6 +738,14 @@  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->shares_media_device and
+		 * then call the snd_media_device_delete(). Don't have
+		 * access to the quirk here. snd_media_device_delete()
+		 * accesses mixer_list
+		 */
+		snd_media_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 ac785d15ced4..5dd3538ed6b5 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -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 {
diff --git a/sound/usb/media.c b/sound/usb/media.c
new file mode 100644
index 000000000000..eb6fe13523c8
--- /dev/null
+++ b/sound/usb/media.c
@@ -0,0 +1,321 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * media.c - Media Controller specific ALSA driver code
+ *
+ * Copyright (c) 2018 Shuah Khan <shuah@kernel.org>
+ *
+ */
+
+/*
+ * This file adds Media Controller support to the ALSA driver
+ * to use the Media Controller API to share the tuner with DVB
+ * and V4L2 drivers that control the media device.
+ *
+ * The media device is created based on the 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 snd_media_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 snd_media_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 snd_media_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 snd_media_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 snd_media_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 snd_media_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 snd_media_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 = snd_media_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 snd_media_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) {
+		snd_media_stream_delete(&stream->substream[0]);
+		snd_media_stream_delete(&stream->substream[1]);
+	}
+
+	snd_media_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 000000000000..0e8a4785f858
--- /dev/null
+++ b/sound/usb/media.h
@@ -0,0 +1,74 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * media.h - Media Controller specific ALSA driver code
+ *
+ * Copyright (c) 2018 Shuah Khan <shuah@kernel.org>
+ *
+ */
+
+/*
+ * This file adds Media Controller support to the ALSA driver
+ * to use the Media Controller API to share the tuner with DVB
+ * and V4L2 drivers that control the media device.
+ *
+ * The media device is created based on the 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 snd_media_device_create(struct snd_usb_audio *chip,
+			    struct usb_interface *iface);
+void snd_media_device_delete(struct snd_usb_audio *chip);
+int snd_media_stream_init(struct snd_usb_substream *subs, struct snd_pcm *pcm,
+			  int stream);
+void snd_media_stream_delete(struct snd_usb_substream *subs);
+int snd_media_start_pipeline(struct snd_usb_substream *subs);
+void snd_media_stop_pipeline(struct snd_usb_substream *subs);
+#else
+static inline int snd_media_device_create(struct snd_usb_audio *chip,
+					  struct usb_interface *iface)
+						{ return 0; }
+static inline void snd_media_device_delete(struct snd_usb_audio *chip) { }
+static inline int snd_media_stream_init(struct snd_usb_substream *subs,
+					struct snd_pcm *pcm, int stream)
+						{ return 0; }
+static inline void snd_media_stream_delete(struct snd_usb_substream *subs) { }
+static inline int snd_media_start_pipeline(struct snd_usb_substream *subs)
+					{ return 0; }
+static inline void snd_media_stop_pipeline(struct snd_usb_substream *subs) { }
+#endif
+#endif /* __MEDIA_H */
diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index 3d12af8bf191..394cd9107507 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -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;
 };
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 382847154227..538ed10ab66d 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
@@ -776,6 +777,10 @@  static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 	struct audioformat *fmt;
 	int ret;
 
+	ret = snd_media_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:
+	snd_media_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;
 
+	snd_media_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 = snd_media_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);
+	snd_media_stop_pipeline(subs);
 
 	if (!as->chip->keep_iface &&
 	    subs->interface >= 0 &&
diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index 37fc0447c071..85c7bdaad922 100644
--- a/sound/usb/quirks-table.h
+++ b/sound/usb/quirks-table.h
@@ -2887,6 +2887,7 @@  YAMAHA_DEVICE(0x7010, "UB99"),
 		.product_name = pname, \
 		.ifnum = QUIRK_ANY_INTERFACE, \
 		.type = QUIRK_AUDIO_ALIGN_TRANSFER, \
+		.shares_media_device = 1, \
 	} \
 }
 
diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 67cf849aa16b..f19d53445f38 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -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);
+	snd_media_stream_delete(subs);
 }
 
 
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index b9faeca645fd..0968a45c8925 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;
@@ -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...) \
@@ -117,6 +122,7 @@  struct snd_usb_audio_quirk {
 	const char *profile_name;	/* override the card->longname */
 	int16_t ifnum;
 	uint16_t type;
+	bool shares_media_device;
 	const void *data;
 };