On 11/14/2016 06:40 AM, Sakari Ailus wrote:
> Hi Shuah,
>
> On Tue, Nov 08, 2016 at 12:20:29PM -0700, Shuah Khan wrote:
>> On Tue, Nov 8, 2016 at 6:55 AM, Sakari Ailus
>> <sakari.ailus@xxxxxxxxxxxxxxx> wrote:
>>> From: Sakari Ailus <sakari.ailus@xxxxxx>
>>>
>>> Allow allocating the media device dynamically. As the struct media_device
>>> embeds struct media_devnode, the lifetime of that object is that same than
>>> that of the media_device.
>>>
>>> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
>>> ---
>>> drivers/media/media-device.c | 15 +++++++++++++++
>>> include/media/media-device.h | 13 +++++++++++++
>>> 2 files changed, 28 insertions(+)
>>>
>>> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
>>> index a31329d..496195e 100644
>>> --- a/drivers/media/media-device.c
>>> +++ b/drivers/media/media-device.c
>>> @@ -684,6 +684,21 @@ void media_device_init(struct media_device *mdev)
>>> }
>>> EXPORT_SYMBOL_GPL(media_device_init);
>>>
>>> +struct media_device *media_device_alloc(struct device *dev)
>>> +{
>>> + struct media_device *mdev;
>>> +
>>> + mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
>>> + if (!mdev)
>>> + return NULL;
>>> +
>>> + mdev->dev = dev;
>>> + media_device_init(mdev);
>>> +
>>> + return mdev;
>>> +}
>>> +EXPORT_SYMBOL_GPL(media_device_alloc);
>>> +
>>
>> One problem with this allocation is, this media device can't be shared across
>> drivers. For au0828 and snd-usb-audio should be able to share the
>> media_device. That is what the Media Allocator API patch series does.
>> This a quick review and I will review the patch series and get back to
>> you.
>
> The assumption has always been there that a media device has a single struct
> device related to it. It hasn't been visible in the function call API
> though, just in the data structures.
>
> I have to admit I may have forgotten something that was discussed back then,
> but do you need to share the same media device over multiple devices in the
> system? I don't see that at least in the allocator patch itself. It's
> "[PATCH v3] media: Media Device Allocator API", isn't it?
>
Hi Sakari,
Remember the work I am doing that adds Media Controller API to snd-usb-audio
and au0828 so they can share the media resources. That is where we need the
media device sharable. Please see the following: this patch series includes
the API and au0828 change to use it. I tested it with snd-usb-audio change,
didn't include it at that time.
https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg98793.html
https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg97779.html
https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg97704.html
I am going to be sending the rebased Media Device Allocator patches with both
au0828 and snd-usb-audio using it in a couple of days. No code changes, just
rebased to Linux 4.9-rc4
thanks,
-- Shuah
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