[RFC PATCH 0/3] Refactoring Videobuf2 for common use

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Hello everybody,

This patch series refactories exsiting Videobuf2, so that not only V4L2
but also other frameworks can use it to manage buffer and utilize
queue.

I would separate existing Videobuf2-core framework into two parts - common
and v4l2-specific part. This work is as follows :

1. Separate existing vb2_buffer structure into common buffer and
   v4l2-specific parts by removing v4l2-specific members and
   embedding it into vb2_v4l2_buffer structure like this:

    struct vb2_v4l2_buffer {
        struct vb2_buffer    vb2;
        struct v4l2_buffer   v4l2_buf;
        struct v4l2_plane    v4l2_planes[VIDEO_MAX_PLANES];
    };

2. Abstract the v4l2-specific elements, and specify them when the device
   drives use them. For example, vb2_v4l2_buffer structure can be abstracted
   by vb2_buffer structure, and device drivers can get framework-specific
   object such as vb2_v4l2_buffer by using container_of().

3. Separate VB2-core framework into real VB2-core and v4l2-specific part.
   This means that it moves V4L2-specific parts of VB2-core to v4l2-specific
   part because current VB2-core framework has some codes dependent of V4L2.
   As a result, we will have two VB2 files - videobuf2-core.c and
   videobuf2-v4l2.c.

Why do we try to make the VB2 framework to be common?

As you may know, current DVB framework uses ringbuffer mechanism to demux
MPEG-2 TS data and pass it to userspace. However, this mechanism requires
extra memory copy because DVB framework provides only read() system call for
application - read() system call copies the kernel data to user-space buffer.

So if we can use VB2 framework which supports streaming I/O and buffer
sharing mechanism, then we could enhance existing DVB framework by removing
the extra memory copy - with VB2 framework, application can access the kernel
data directly through mmap system call.

This patch series is the first step for it.

We have a plan for this work as follows:

1. Separate existing VB2 framework into three parts - VB2 common, VB2-v4l2,
   and VB2-dvb. Of course, this change should not affect other v4l2-based
   device drivers. This patch series includes some parts of this step.

2. Add new APIs for DVB streaming I/O. These APIs will be implemented
   in VB2-dvb framework. So, we can remove unnecessary memory copy between
   kernel-space and user-space by using these new APIs.
   However, we leaves legacy interfaces as-is for backward compatibility.

We are working on this project with Mauro and have a discussion with him
on IRC channel weekly. Nowaday, we are discussing more detailed DVB user
scenario for streaming I/O.

The final goal of this project is to enhance current DVB framework.
The first mission is to achieve zero-copy functionality between kernel-space
and user-space with mmap system call. More missions are under consideration:
i.e., we could share the buffer not only between kernel-space and user-space
but also between devices - demux, hw video codec - by exporting a buffer
to dmabuf fd with VB2 framework.

Any suggestions and comments are welcome.

Best regards,
Junghak

Junghak Sung (3):
  modify the vb2_buffer structure for common video buffer     and make
    struct vb2_v4l2_buffer
  move struct vb2_queue to common and apply the changes related with
    that     Signed-off-by: Junghak Sung <jh1009.sung@xxxxxxxxxxx>
  make vb2-core part with not v4l2-specific elements

 Documentation/video4linux/v4l2-pci-skeleton.c      |   16 +-
 drivers/media/dvb-frontends/rtl2832_sdr.c          |   13 +-
 drivers/media/pci/cx23885/cx23885-417.c            |   13 +-
 drivers/media/pci/cx23885/cx23885-core.c           |    4 +-
 drivers/media/pci/cx23885/cx23885-dvb.c            |   12 +-
 drivers/media/pci/cx23885/cx23885-vbi.c            |   17 +-
 drivers/media/pci/cx23885/cx23885-video.c          |   19 +-
 drivers/media/pci/cx23885/cx23885.h                |    2 +-
 drivers/media/pci/cx25821/cx25821-video.c          |   20 +-
 drivers/media/pci/cx25821/cx25821.h                |    2 +-
 drivers/media/pci/cx88/cx88-blackbird.c            |   15 +-
 drivers/media/pci/cx88/cx88-core.c                 |    2 +-
 drivers/media/pci/cx88/cx88-dvb.c                  |   13 +-
 drivers/media/pci/cx88/cx88-mpeg.c                 |    2 +-
 drivers/media/pci/cx88/cx88-vbi.c                  |   17 +-
 drivers/media/pci/cx88/cx88-video.c                |   17 +-
 drivers/media/pci/cx88/cx88.h                      |    2 +-
 drivers/media/pci/saa7134/saa7134-core.c           |    4 +-
 drivers/media/pci/saa7134/saa7134-ts.c             |   28 +-
 drivers/media/pci/saa7134/saa7134-vbi.c            |   22 +-
 drivers/media/pci/saa7134/saa7134-video.c          |   17 +-
 drivers/media/pci/saa7134/saa7134.h                |    8 +-
 drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c     |   19 +-
 drivers/media/pci/solo6x10/solo6x10-v4l2.c         |   11 +-
 drivers/media/pci/solo6x10/solo6x10.h              |    4 +-
 drivers/media/pci/sta2x11/sta2x11_vip.c            |   24 +-
 drivers/media/pci/tw68/tw68-video.c                |   20 +-
 drivers/media/pci/tw68/tw68.h                      |    2 +-
 drivers/media/platform/am437x/am437x-vpfe.c        |   33 +-
 drivers/media/platform/am437x/am437x-vpfe.h        |    2 +-
 drivers/media/platform/blackfin/bfin_capture.c     |   30 +-
 drivers/media/platform/coda/coda-bit.c             |   20 +-
 drivers/media/platform/coda/coda-common.c          |   28 +-
 drivers/media/platform/coda/coda-jpeg.c            |    2 +-
 drivers/media/platform/coda/coda.h                 |    6 +-
 drivers/media/platform/davinci/vpbe_display.c      |   25 +-
 drivers/media/platform/davinci/vpif_capture.c      |   30 +-
 drivers/media/platform/davinci/vpif_capture.h      |    2 +-
 drivers/media/platform/davinci/vpif_display.c      |   34 +-
 drivers/media/platform/davinci/vpif_display.h      |    6 +-
 drivers/media/platform/exynos-gsc/gsc-core.c       |    2 +-
 drivers/media/platform/exynos-gsc/gsc-core.h       |    6 +-
 drivers/media/platform/exynos-gsc/gsc-m2m.c        |   12 +-
 drivers/media/platform/exynos4-is/fimc-capture.c   |   23 +-
 drivers/media/platform/exynos4-is/fimc-core.c      |    4 +-
 drivers/media/platform/exynos4-is/fimc-core.h      |    6 +-
 drivers/media/platform/exynos4-is/fimc-is.h        |    2 +-
 drivers/media/platform/exynos4-is/fimc-isp-video.c |   25 +-
 drivers/media/platform/exynos4-is/fimc-isp-video.h |    2 +-
 drivers/media/platform/exynos4-is/fimc-isp.h       |    4 +-
 drivers/media/platform/exynos4-is/fimc-lite.c      |   25 +-
 drivers/media/platform/exynos4-is/fimc-lite.h      |    4 +-
 drivers/media/platform/exynos4-is/fimc-m2m.c       |   14 +-
 drivers/media/platform/m2m-deinterlace.c           |   16 +-
 drivers/media/platform/marvell-ccic/mcam-core.c    |   26 +-
 drivers/media/platform/marvell-ccic/mcam-core.h    |    2 +-
 drivers/media/platform/mx2_emmaprp.c               |   16 +-
 drivers/media/platform/omap3isp/ispvideo.c         |   24 +-
 drivers/media/platform/omap3isp/ispvideo.h         |    4 +-
 drivers/media/platform/s3c-camif/camif-capture.c   |   23 +-
 drivers/media/platform/s3c-camif/camif-core.c      |    2 +-
 drivers/media/platform/s3c-camif/camif-core.h      |    4 +-
 drivers/media/platform/s5p-g2d/g2d.c               |   14 +-
 drivers/media/platform/s5p-jpeg/jpeg-core.c        |   34 +-
 drivers/media/platform/s5p-mfc/s5p_mfc.c           |   14 +-
 drivers/media/platform/s5p-mfc/s5p_mfc_common.h    |    4 +-
 drivers/media/platform/s5p-mfc/s5p_mfc_dec.c       |   36 +-
 drivers/media/platform/s5p-mfc/s5p_mfc_enc.c       |   57 +-
 drivers/media/platform/s5p-mfc/s5p_mfc_opr_v5.c    |    4 +-
 drivers/media/platform/s5p-mfc/s5p_mfc_opr_v6.c    |    4 +-
 drivers/media/platform/s5p-tv/mixer.h              |    4 +-
 drivers/media/platform/s5p-tv/mixer_reg.c          |    2 +-
 drivers/media/platform/s5p-tv/mixer_video.c        |   11 +-
 drivers/media/platform/sh_veu.c                    |   25 +-
 drivers/media/platform/soc_camera/atmel-isi.c      |   26 +-
 drivers/media/platform/soc_camera/mx2_camera.c     |   41 +-
 drivers/media/platform/soc_camera/mx3_camera.c     |   34 +-
 drivers/media/platform/soc_camera/rcar_vin.c       |   30 +-
 .../platform/soc_camera/sh_mobile_ceu_camera.c     |   47 +-
 drivers/media/platform/soc_camera/soc_camera.c     |    2 +-
 drivers/media/platform/ti-vpe/vpe.c                |   30 +-
 drivers/media/platform/vim2m.c                     |   28 +-
 drivers/media/platform/vivid/vivid-core.h          |    4 +-
 drivers/media/platform/vivid/vivid-kthread-cap.c   |    8 +-
 drivers/media/platform/vivid/vivid-kthread-out.c   |    8 +-
 drivers/media/platform/vivid/vivid-sdr-cap.c       |   18 +-
 drivers/media/platform/vivid/vivid-vbi-cap.c       |   14 +-
 drivers/media/platform/vivid/vivid-vbi-out.c       |   14 +-
 drivers/media/platform/vivid/vivid-vid-cap.c       |   24 +-
 drivers/media/platform/vivid/vivid-vid-out.c       |   21 +-
 drivers/media/platform/vsp1/vsp1_rpf.c             |    4 +-
 drivers/media/platform/vsp1/vsp1_video.c           |   20 +-
 drivers/media/platform/vsp1/vsp1_video.h           |    6 +-
 drivers/media/platform/vsp1/vsp1_wpf.c             |    4 +-
 drivers/media/usb/airspy/airspy.c                  |   15 +-
 drivers/media/usb/au0828/au0828-vbi.c              |   17 +-
 drivers/media/usb/au0828/au0828-video.c            |   29 +-
 drivers/media/usb/au0828/au0828.h                  |    2 +-
 drivers/media/usb/em28xx/em28xx-vbi.c              |   15 +-
 drivers/media/usb/em28xx/em28xx-video.c            |   30 +-
 drivers/media/usb/em28xx/em28xx.h                  |    2 +-
 drivers/media/usb/go7007/go7007-driver.c           |    2 +-
 drivers/media/usb/go7007/go7007-priv.h             |    4 +-
 drivers/media/usb/go7007/go7007-v4l2.c             |   15 +-
 drivers/media/usb/hackrf/hackrf.c                  |   13 +-
 drivers/media/usb/msi2500/msi2500.c                |   13 +-
 drivers/media/usb/pwc/pwc-if.c                     |   26 +-
 drivers/media/usb/pwc/pwc.h                        |    2 +-
 drivers/media/usb/s2255/s2255drv.c                 |   16 +-
 drivers/media/usb/stk1160/stk1160-v4l.c            |   15 +-
 drivers/media/usb/stk1160/stk1160-video.c          |    2 +-
 drivers/media/usb/stk1160/stk1160.h                |    4 +-
 drivers/media/usb/usbtv/usbtv-video.c              |   11 +-
 drivers/media/usb/usbtv/usbtv.h                    |    2 +-
 drivers/media/usb/uvc/uvc_queue.c                  |   32 +-
 drivers/media/usb/uvc/uvcvideo.h                   |    4 +-
 drivers/media/v4l2-core/Makefile                   |    2 +-
 drivers/media/v4l2-core/v4l2-ioctl.c               |    2 +-
 drivers/media/v4l2-core/v4l2-mem2mem.c             |    8 +-
 drivers/media/v4l2-core/videobuf2-core.c           | 1888 ++------------------
 drivers/media/v4l2-core/videobuf2-dma-contig.c     |    2 +-
 drivers/media/v4l2-core/videobuf2-dma-sg.c         |    2 +-
 drivers/media/v4l2-core/videobuf2-dvb.c            |    2 +-
 drivers/media/v4l2-core/videobuf2-memops.c         |    2 +-
 drivers/media/v4l2-core/videobuf2-v4l2.c           | 1878 +++++++++++++++++++
 drivers/media/v4l2-core/videobuf2-vmalloc.c        |    2 +-
 drivers/staging/media/davinci_vpfe/vpfe_video.c    |   30 +-
 drivers/staging/media/davinci_vpfe/vpfe_video.h    |    2 +-
 drivers/staging/media/dt3155v4l/dt3155v4l.c        |   14 +-
 drivers/staging/media/dt3155v4l/dt3155v4l.h        |    2 +-
 drivers/staging/media/omap4iss/iss_video.c         |   16 +-
 drivers/staging/media/omap4iss/iss_video.h         |    4 +-
 drivers/usb/gadget/function/uvc_queue.c            |   14 +-
 drivers/usb/gadget/function/uvc_queue.h            |    4 +-
 include/media/davinci/vpbe_display.h               |    2 +-
 include/media/soc_camera.h                         |    2 +-
 include/media/v4l2-mem2mem.h                       |   10 +-
 include/media/videobuf2-core.h                     |  235 ++-
 include/media/videobuf2-dma-contig.h               |    6 +-
 include/media/videobuf2-dma-sg.h                   |    6 +-
 include/media/videobuf2-dvb.h                      |    2 +-
 include/media/videobuf2-memops.h                   |    2 +-
 include/media/videobuf2-v4l2.h                     |  139 ++
 include/media/videobuf2-vmalloc.h                  |    2 +-
 144 files changed, 3290 insertions(+), 2662 deletions(-)
 create mode 100644 drivers/media/v4l2-core/videobuf2-v4l2.c
 create mode 100644 include/media/videobuf2-v4l2.h

-- 
1.7.9.5

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