Re: [RFC PATCH v2 4/5] media: videobuf2: Define vb2_buf_type and vb2_memory

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hello,

On Monday 10 August 2015 10:22:12 Hans Verkuil wrote:
> On 07/31/2015 10:44 AM, Junghak Sung wrote:
> > Define enum vb2_buf_type and enum vb2_memory for videobuf2-core. This
> > change requires translation functions that could covert v4l2-core stuffs
> > to videobuf2-core stuffs in videobuf2-v4l2.c file.
> > The v4l2-specific member variables(e.g. type, memory) remains in
> > struct vb2_queue for backward compatibility and performance of type
> > translation.
> > 
> > Signed-off-by: Junghak Sung <jh1009.sung@samsung.com>
> > Signed-off-by: Geunyoung Kim <nenggun.kim@samsung.com>
> > Acked-by: Seung-Woo Kim <sw0312.kim@samsung.com>
> > Acked-by: Inki Dae <inki.dae@samsung.com>
> > ---
> > 
> >  drivers/media/v4l2-core/videobuf2-core.c |  139 +++++++++++---------
> >  drivers/media/v4l2-core/videobuf2-v4l2.c |  209 ++++++++++++++++++-------
> >  include/media/videobuf2-core.h           |   99 +++++++++++---
> >  include/media/videobuf2-v4l2.h           |   12 +-
> >  4 files changed, 299 insertions(+), 160 deletions(-)
> 
> <snip>
> 
> > diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c
> > b/drivers/media/v4l2-core/videobuf2-v4l2.c index 85527e9..22dd19c 100644
> > --- a/drivers/media/v4l2-core/videobuf2-v4l2.c
> > +++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
> > @@ -30,8 +30,46 @@
> > 
> >  #include <media/v4l2-common.h>
> >  #include <media/videobuf2-v4l2.h>
> > 
> > +#define CREATE_TRACE_POINTS
> > 
> >  #include <trace/events/v4l2.h>
> > 
> > +static const enum vb2_buf_type _tbl_buf_type[] = {
> > +	[V4L2_BUF_TYPE_VIDEO_CAPTURE]		= VB2_BUF_TYPE_VIDEO_CAPTURE,
> > +	[V4L2_BUF_TYPE_VIDEO_OUTPUT]		= VB2_BUF_TYPE_VIDEO_OUTPUT,
> > +	[V4L2_BUF_TYPE_VIDEO_OVERLAY]		= VB2_BUF_TYPE_VIDEO_OVERLAY,
> > +	[V4L2_BUF_TYPE_VBI_CAPTURE]		= VB2_BUF_TYPE_VBI_CAPTURE,
> > +	[V4L2_BUF_TYPE_VBI_OUTPUT]		= VB2_BUF_TYPE_VBI_OUTPUT,
> > +	[V4L2_BUF_TYPE_SLICED_VBI_CAPTURE]	= 
VB2_BUF_TYPE_SLICED_VBI_CAPTURE,
> > +	[V4L2_BUF_TYPE_SLICED_VBI_OUTPUT]	= VB2_BUF_TYPE_SLICED_VBI_OUTPUT,
> > +	[V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY]	=
> > VB2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY,
> > +	[V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE]	=
> > VB2_BUF_TYPE_VIDEO_CAPTURE_MPLANE,
> > +	[V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE]	= 
VB2_BUF_TYPE_VIDEO_OUTPUT_MPLANE,
> > +	[V4L2_BUF_TYPE_SDR_CAPTURE]		= VB2_BUF_TYPE_SDR_CAPTURE,
> > +	[V4L2_BUF_TYPE_PRIVATE]			= VB2_BUF_TYPE_PRIVATE,
> > +};
> > +
> > +static const enum vb2_memory _tbl_memory[] = {
> > +	[V4L2_MEMORY_MMAP]	= VB2_MEMORY_MMAP,
> > +	[V4L2_MEMORY_USERPTR]	= VB2_MEMORY_USERPTR,
> > +	[V4L2_MEMORY_DMABUF]	= VB2_MEMORY_DMABUF,
> > +};
> > +
> > +#define to_vb2_buf_type(type)					\
> > +({								\
> > +	enum vb2_buf_type ret = 0;				\
> > +	if( type > 0 && type < ARRAY_SIZE(_tbl_buf_type) )	\
> > +		ret = (_tbl_buf_type[type]);			\
> > +	ret;							\
> > +})
> > +
> > +#define to_vb2_memory(memory)					\
> > +({								\
> > +	enum vb2_memory ret = 0;				\
> > +	if( memory > 0 && memory < ARRAY_SIZE(_tbl_memory) )	\
> > +		ret = (_tbl_memory[memory]);			\
> > +	ret;							\
> > +})
> > +
> 
> <snip>
> 
> > diff --git a/include/media/videobuf2-core.h
> > b/include/media/videobuf2-core.h index dc405da..871fcc6 100644
> > --- a/include/media/videobuf2-core.h
> > +++ b/include/media/videobuf2-core.h
> > @@ -15,9 +15,47 @@
> > 
> >  #include <linux/mm_types.h>
> >  #include <linux/mutex.h>
> >  #include <linux/poll.h>
> > 
> > -#include <linux/videodev2.h>
> > 
> >  #include <linux/dma-buf.h>
> > 
> > +#define VB2_MAX_FRAME               32
> > +#define VB2_MAX_PLANES               8
> > +
> > +enum vb2_buf_type {
> > +	VB2_BUF_TYPE_UNKNOWN			= 0,
> > +	VB2_BUF_TYPE_VIDEO_CAPTURE		= 1,
> > +	VB2_BUF_TYPE_VIDEO_OUTPUT		= 2,
> > +	VB2_BUF_TYPE_VIDEO_OVERLAY		= 3,
> > +	VB2_BUF_TYPE_VBI_CAPTURE		= 4,
> > +	VB2_BUF_TYPE_VBI_OUTPUT			= 5,
> > +	VB2_BUF_TYPE_SLICED_VBI_CAPTURE		= 6,
> > +	VB2_BUF_TYPE_SLICED_VBI_OUTPUT		= 7,
> > +	VB2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY	= 8,
> > +	VB2_BUF_TYPE_VIDEO_CAPTURE_MPLANE	= 9,
> > +	VB2_BUF_TYPE_VIDEO_OUTPUT_MPLANE	= 10,
> > +	VB2_BUF_TYPE_SDR_CAPTURE		= 11,
> > +	VB2_BUF_TYPE_DVB_CAPTURE		= 12,
> > +	VB2_BUF_TYPE_PRIVATE			= 0x80,
> > +};
> > +
> > +enum vb2_memory {
> > +	VB2_MEMORY_UNKNOWN	= 0,
> > +	VB2_MEMORY_MMAP		= 1,
> > +	VB2_MEMORY_USERPTR	= 2,
> > +	VB2_MEMORY_DMABUF	= 4,
> > +};
> > +
> > +#define VB2_TYPE_IS_MULTIPLANAR(type)			\
> > +	((type) == VB2_BUF_TYPE_VIDEO_CAPTURE_MPLANE	\
> > +	 || (type) == VB2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
> > +
> > +#define VB2_TYPE_IS_OUTPUT(type)				\
> > +	((type) == VB2_BUF_TYPE_VIDEO_OUTPUT			\
> > +	 || (type) == VB2_BUF_TYPE_VIDEO_OUTPUT_MPLANE		\
> > +	 || (type) == VB2_BUF_TYPE_VIDEO_OVERLAY		\
> > +	 || (type) == VB2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY		\
> > +	 || (type) == VB2_BUF_TYPE_VBI_OUTPUT			\
> > +	 || (type) == VB2_BUF_TYPE_SLICED_VBI_OUTPUT)
> 
> You don't actually need to create vb2_buf_type: unless I am mistaken, all
> that the vb2 core needs to know is if it is a capture or output queue and
> possibly (not sure about that) if it is single or multiplanar. So add
> fields to the vb2_queue struct for that information and leave the buf_type
> to the v4l2 specific header and code.
> 
> You also don't need the _tbl_memory[] array. All you need to do is to check
> in videobuf2-v4l2.c that VB2_MEMORY* equals the V4L2_MEMORY_* defines and
> generate a #error if not:
> 
> #if VB2_MEMORY_MMAP != V4L2_MEMORY_MMAP || VB2_MEMORY_....
> #error VB2_MEMORY_* != V4L2_MEMORY_*!
> #endif

Hijacking this e-mail thread a bit, would it make sense for the new vb2-core 
to support different memory allocation for different planes ? I'm foreseeing 
use cases for buffers that bundle image data with meta-data, where image data 
should be captured to a dma-buf imported buffer, but meta-data doesn't need to 
be shared. In that case it wouldn't be easy for userspace to find a dma-buf 
provider for the meta-data buffers in order to import all planes. Being able 
to use dma-buf import for the image plane(s) and mmap for the meta-data plane 
would be easier.

-- 
Regards,

Laurent Pinchart