On Tuesday, September 27, 2011 13:00:24 Guennadi Liakhovetski wrote: > Hi Hans > > On Tue, 27 Sep 2011, Hans Verkuil wrote: > > > On Thursday, September 08, 2011 09:45:15 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.liakhovetski@xxxxxx> > > > --- > > > > > > v7: added the "experimental" comment, as suggested by Sakari - thanks. > > > > > > drivers/media/video/v4l2-compat-ioctl32.c | 67 +++++++++++++++++++++++++--- > > > drivers/media/video/v4l2-ioctl.c | 29 ++++++++++++ > > > include/linux/videodev2.h | 17 +++++++ > > > include/media/v4l2-ioctl.h | 2 + > > > 4 files changed, 107 insertions(+), 8 deletions(-) > > [snip] > > > > diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h > > > index a5359c6..6e87ea9 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 > > > @@ -2098,6 +2101,15 @@ 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 > > > * > > > @@ -2188,6 +2200,11 @@ 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 _IOW('V', 93, struct v4l2_buffer) > > > > I think I would prefer _IOWR here. QBUF etc. also use IOWR and you never know > > what you might return in the future. At the very least using IOWR allows us > > to update the state field, which would be a perfectly reasonable thing to do. > > Sorry, which state field do you mean? We have already marked these ioctl() > as experimental, isn't this enough? The state field in the v4l2_buffer argument. The experimental tag allows for changes, that's true. So this is my proposed change :-) Regards, Hans > > Thanks > Guennadi > --- > Guennadi Liakhovetski, Ph.D. > Freelance Open-Source Software Developer > http://www.open-technology.de/ > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html