Re: [PATCH 05/12] [media] vivid: assign the specific device to the vb2_queue->dev

[Gustavo Padovan <gustavo@padovan.org>]

2017-07-07 Shuah Khan <shuahkh@osg.samsung.com>:

> On 06/16/2017 01:39 AM, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.com>
> > 
> > Instead of assigning the global v4l2 device, assign the specific device.
> > This was causing trouble when using using V4L2 events with vivid
> > devices. The device's queue should be the same we opened in userspace.
> > 
> > Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
> > ---
> >  drivers/media/platform/vivid/vivid-core.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/media/platform/vivid/vivid-core.c b/drivers/media/platform/vivid/vivid-core.c
> > index ef344b9..8843170 100644
> > --- a/drivers/media/platform/vivid/vivid-core.c
> > +++ b/drivers/media/platform/vivid/vivid-core.c
> > @@ -1070,7 +1070,7 @@ static int vivid_create_instance(struct platform_device *pdev, int inst)
> >  		q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> >  		q->min_buffers_needed = 2;
> >  		q->lock = &dev->mutex;
> > -		q->dev = dev->v4l2_dev.dev;
> > +		q->dev = &dev->vid_cap_dev.dev;
> 
> Does this work in all cases? My concern is that in some code paths
> q->dev might be used to initiate release perhaps.
> 
> Fore example v4l2_dev.release is vivid_dev_release()
> dev->v4l2_dev.release = vivid_dev_release;
> 
> vid_cap_dev release is video_device_release_empty
> 
> This is one difference, but there might be others and the code paths
> that might depend on q->dev being the v4l2_dev.dev which is the global
> dev.

The release call comes from the v4l2-core as we pass the v4l2 device on
v4l2_register_device(). q->dev is in just one ocasion and setting it to
a different device doesn't change the behavior. That code just check if
it is queued or not.

Gustavo