On Wed, 28 Sep 2011, Guennadi Liakhovetski wrote:
> Hi Hans
>
> On Wed, 28 Sep 2011, Hans Verkuil wrote:
>
> > On Tuesday, September 27, 2011 18:54:53 Guennadi Liakhovetski wrote:
> > > A possibility to preallocate and initialise buffers of different sizes
> > > in V4L2 is required for an efficient implementation of a snapshot
> > > mode. This patch adds two new ioctl()s: VIDIOC_CREATE_BUFS and
> > > VIDIOC_PREPARE_BUF and defines respective data structures.
> > >
> > > Signed-off-by: Guennadi Liakhovetski <g.liakhovet...@gmx.de>
> > > ---
> > >
> > > v8: addressed comments from Hans - thanks:
> > >
> > > 1. added checks in ioctl() preprocessing
> > > 2. changed VIDIOC_PREPARE_BUF to _IOWR
> > >
> > > drivers/media/video/v4l2-compat-ioctl32.c | 67
> > > +++++++++++++++++++++++++---
> > > drivers/media/video/v4l2-ioctl.c | 36 +++++++++++++++
> > > include/linux/videodev2.h | 17 +++++++
> > > include/media/v4l2-ioctl.h | 2 +
> > > 4 files changed, 114 insertions(+), 8 deletions(-)
> > >
> >
> > Almost:
> >
> > > diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> > > index 9d14523..7d75dd1 100644
> > > --- a/include/linux/videodev2.h
> > > +++ b/include/linux/videodev2.h
> > > @@ -653,6 +653,9 @@ struct v4l2_buffer {
> > > #define V4L2_BUF_FLAG_ERROR 0x0040
> > > #define V4L2_BUF_FLAG_TIMECODE 0x0100 /* timecode field is valid */
> > > #define V4L2_BUF_FLAG_INPUT 0x0200 /* input field is valid */
> > > +/* Cache handling flags */
> > > +#define V4L2_BUF_FLAG_NO_CACHE_INVALIDATE 0x0400
> > > +#define V4L2_BUF_FLAG_NO_CACHE_CLEAN 0x0800
> > >
> > > /*
> > > * O V E R L A Y P R E V I E W
> > > @@ -2099,6 +2102,15 @@ struct v4l2_dbg_chip_ident {
> > > __u32 revision; /* chip revision, chip specific */
> > > } __attribute__ ((packed));
> > >
> > > +/* VIDIOC_CREATE_BUFS */
> > > +struct v4l2_create_buffers {
> > > + __u32 index; /* output: buffers
> > > index...index + count - 1 have been created */
> > > + __u32 count;
> > > + enum v4l2_memory memory;
> > > + struct v4l2_format format; /* "type" is used always, the
> > > rest if sizeimage == 0 */
> > > + __u32 reserved[8];
> > > +};
> > > +
> > > /*
> > > * I O C T L C O D E S F O R V I D E O D E V I C E S
> > > *
> > > @@ -2189,6 +2201,11 @@ struct v4l2_dbg_chip_ident {
> > > #define VIDIOC_SUBSCRIBE_EVENT _IOW('V', 90, struct
> > > v4l2_event_subscription)
> > > #define VIDIOC_UNSUBSCRIBE_EVENT _IOW('V', 91, struct
> > > v4l2_event_subscription)
> > >
> > > +/* Experimental, the below two ioctls may change over the next couple of
> > > kernel
> > > + versions */
> > > +#define VIDIOC_CREATE_BUFS _IOWR('V', 92, struct
> > > v4l2_create_buffers)
> > > +#define VIDIOC_PREPARE_BUF _IOWR('V', 93, struct v4l2_buffer)
> > > +
> > > /* Reminder: when adding new ioctls please add support for them to
> > > drivers/media/video/v4l2-compat-ioctl32.c as well! */
> > >
> > > diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
> > > index dd9f1e7..55cf8ae 100644
> > > --- a/include/media/v4l2-ioctl.h
> > > +++ b/include/media/v4l2-ioctl.h
> > > @@ -122,6 +122,8 @@ struct v4l2_ioctl_ops {
> > > int (*vidioc_qbuf) (struct file *file, void *fh, struct v4l2_buffer
> > > *b);
> > > int (*vidioc_dqbuf) (struct file *file, void *fh, struct v4l2_buffer
> > > *b);
> > >
> > > + int (*vidioc_create_bufs)(struct file *file, void *fh, struct
> > > v4l2_create_buffers *b);
> > > + int (*vidioc_prepare_buf)(struct file *file, void *fh, const struct
> > > v4l2_buffer *b);
> >
> > If this is IOWR, then there shouldn't be a const here.
>
> hrm... Sure.
>
> > I have been thinking about this a bit more. Currently we only have a
> > V4L2_BUF_FLAG_QUEUED
> > flag and no V4L2_BUF_FLAG_PREPARED flag. I do think we need this after all.
> > The QUEUED flag
> > can't be used here as the buffer isn't queued yet, it's only prepared.
>
> Ok, I can add it to this patch together with the other two cache-handling
> flags. I presume, I shall also add it to
>
> V4L2_BUFFER_STATE_FLAGS
>
> in videobuf2-core.c, otherwise just let drivers and apps go figure?... We
> could set that flag centrally in __buf_prepare(), but since
> V4L2_BUF_FLAG_QUEUED is managed by individual drivers, we probably want to
> leave V4L2_BUF_FLAG_PREPARED like that too?
Good, time to wake up. V4L2_BUF_FLAG_QUEUED is indeed set in
videobuf2-core.c, so, I guess, the same should be done with
V4L2_BUF_FLAG_PREPARED in __fill_v4l2_buffer().
Thanks
Guennadi
> > Regards,
> >
> > Hans
> >
> > >
> > > int (*vidioc_overlay) (struct file *file, void *fh, unsigned int i);
> > > int (*vidioc_g_fbuf) (struct file *file, void *fh,
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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