On Wednesday, September 28, 2011 10:48:33 Guennadi Liakhovetski wrote:
> 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 <[email protected]>
> > > > ---
> > > >
> > > > 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.
Good morning, Guennadi! :-)
> 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().
Yup. Seems sensible to me.
Regards,
Hans
>
> 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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