Re: [RFC PATCH v8 1/4] media: Media Device Allocator API

From: shuah
Date: Thu Dec 06 2018 - 10:33:18 EST


On 11/19/18 1:59 AM, Pavel Machek wrote:
On Thu 2018-11-01 18:31:30, shuah@xxxxxxxxxx wrote:
From: Shuah Khan <shuah@xxxxxxxxxx>

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


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.

thanks,
-- Shuah