linux-kernel - Re: [PATCH 09/31] media: v4l2-core add v4l_vb2q_enable_media

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Date:	Thu, 28 Jan 2016 15:34:39 -0200
From:	Mauro Carvalho Chehab <mchehab@....samsung.com>
To:	Shuah Khan <shuahkh@....samsung.com>
Cc:	tiwai@...e.com, clemens@...isch.de, hans.verkuil@...co.com,
	laurent.pinchart@...asonboard.com, sakari.ailus@...ux.intel.com,
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Subject: Re: [PATCH 09/31] media: v4l2-core add
 v4l_vb2q_enable_media_tuner() helper

Em Thu, 28 Jan 2016 10:31:21 -0700
Shuah Khan <shuahkh@....samsung.com> escreveu:

> On 01/28/2016 08:29 AM, Mauro Carvalho Chehab wrote:
> > Em Wed,  6 Jan 2016 13:26:58 -0700
> > Shuah Khan <shuahkh@....samsung.com> escreveu:
> >   
> >> Add a new v4l_vb2q_enable_media_tuner() wrapper function
> >> to be called from v4l2-core to enable the media tuner with
> >> videobuf2 queue, when the calling frunction has the videobuf2
> >> queue and doesn't have the struct video_device associated with
> >> the queue handy as in the case of vb2_core_streamon(). This
> >> function simply calls v4l_enable_media_tuner() passing in the
> >> pointer to struct video_device.
> >>
> >> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
> >> ---
> >>  drivers/media/v4l2-core/v4l2-dev.c | 21 +++++++++++++++++++++
> >>  include/media/v4l2-dev.h           |  1 +
> >>  2 files changed, 22 insertions(+)
> >>
> >> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
> >> index f06da6e..9ef675a 100644
> >> --- a/drivers/media/v4l2-core/v4l2-dev.c
> >> +++ b/drivers/media/v4l2-core/v4l2-dev.c
> >> @@ -30,6 +30,7 @@
> >>  #include <media/v4l2-common.h>
> >>  #include <media/v4l2-device.h>
> >>  #include <media/v4l2-ioctl.h>
> >> +#include <media/videobuf2-core.h>
> >>  
> >>  #define VIDEO_NUM_DEVICES	256
> >>  #define VIDEO_NAME              "video4linux"
> >> @@ -261,6 +262,26 @@ void v4l_disable_media_tuner(struct video_device *vdev)
> >>  }
> >>  EXPORT_SYMBOL_GPL(v4l_disable_media_tuner);
> >>  
> >> +/**
> >> + * v4l_vb2q_enable_media_tuner - Wrapper for v4l_enable_media_tuner()
> >> + * @q:         videobuf2 queue
> >> + *
> >> + * This function is intended to be called from v4l2-core
> >> + * to enable the media tuner with videobuf2 queue, when
> >> + * the calling frunction has the videobuf2 queue and doesn't  
> > 
> > 	typo: function  
> 
> ok thanks
> 
> >   
> >> + * have the struct video_device associated with the
> >> + * queue handy as in the case of vb2_core_streamon(). This
> >> + * function simply calls v4l_enable_media_tuner() passing
> >> + * in the pointer to struct video_device.  
> > 
> > The hole description seems confusing. I'm not seeing the light
> > about why this is needed.  
> 
> Sorry if the description isn't clear. During videobuf2
> work, owner field in struct vb2_queue is changed from
> struct v4l2_fh * to void. Prior to this work, I could
> call v4l_enable_media_tuner(). 
> 
> +               ret = v4l_enable_media_tuner(q->owner->vdev);
> +               if (ret)
> +                       return ret;
> 
> As you can see with the videobuf2, to be able to call
> v4l_enable_media_tuner() from vb2_core_streamon(), I have
> had to this wrapper to maintain the abstraction introduced
> in videobuf2 work.
> 
> Hope this helps the need for this wrapper.


It is clearer now. Please improve the description of the patch
on the next version for us to remember ;)

Regards,
Mauro
> 
> thanks,
> -- Shuah
> >   
> >> + */
> >> +int v4l_vb2q_enable_media_tuner(struct vb2_queue *q)
> >> +{
> >> +	struct v4l2_fh *fh = q->owner;
> >> +
> >> +	return v4l_enable_media_tuner(fh->vdev);
> >> +}
> >> +EXPORT_SYMBOL_GPL(v4l_vb2q_enable_media_tuner);
> >> +
> >>  /* Priority handling */
> >>  
> >>  static inline bool prio_is_valid(enum v4l2_priority prio)
> >> diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
> >> index 68999a3..1948097 100644
> >> --- a/include/media/v4l2-dev.h
> >> +++ b/include/media/v4l2-dev.h
> >> @@ -179,6 +179,7 @@ struct video_device * __must_check video_device_alloc(void);
> >>  
> >>  int v4l_enable_media_tuner(struct video_device *vdev);
> >>  void v4l_disable_media_tuner(struct video_device *vdev);
> >> +int v4l_vb2q_enable_media_tuner(struct vb2_queue *q);  
> > 
> > Documentation?
> >   
> >>  
> >>  /* this release function frees the vdev pointer */
> >>  void video_device_release(struct video_device *vdev);  
> 
>