linux-kernel - Re: [alsa-devel] [PATCH v9 4/4] sound/usb: Use Media Controller API to share media resources

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Date:   Fri, 11 Jan 2019 15:59:54 +0100
From:   Hans Verkuil <hverkuil@...all.nl>
To:     shuah <shuah@...nel.org>, mchehab@...nel.org
Cc:     Takashi Iwai <tiwai@...e.de>, perex@...ex.cz, tiwai@...e.com,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org
Subject: Re: [alsa-devel] [PATCH v9 4/4] sound/usb: Use Media Controller API
 to share media resources

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@...nel.org wrote:
>>>
>>> From: Shuah Khan <shuah@...nel.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@...nel.org>
>>
>> Feel free to take my ack regarding the sound stuff:
>>    Reviewed-by: Takashi Iwai <tiwai@...e.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