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.
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.
Regards,
Hans
>
> int (*vidioc_overlay) (struct file *file, void *fh, unsigned int i);
> int (*vidioc_g_fbuf) (struct file *file, void *fh,
>
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