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 07:57:49 -0700
From:   shuah <shuah@...nel.org>
To:     mchehab@...nel.org
Cc:     Takashi Iwai <tiwai@...e.de>, perex@...ex.cz, tiwai@...e.com,
        hverkuil@...all.nl, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        shuah <shuah@...nel.org>
Subject: Re: [alsa-devel] [PATCH v9 4/4] sound/usb: Use Media Controller API
 to share media resources

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?

thanks,
-- Shuah