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 08:04:00 -0700
From:   shuah <shuah@...nel.org>
To:     Hans Verkuil <hverkuil@...all.nl>, 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, shuah <shuah@...nel.org>
Subject: Re: [alsa-devel] [PATCH v9 4/4] sound/usb: Use Media Controller API
 to share media resources

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@...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
> 

Hans,

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

thanks,
-- Shuah