Hi Hans,
Thanks for the patch.
On Sat, Jan 26, 2019 at 12:06:19PM +0100, Hans Verkuil wrote:
> This patch adds an extended version of VIDIOC_DQEVENT that:
>
> 1) is Y2038 safe by using a __u64 for the timestamp
> 2) needs no compat32 conversion code
> 3) is able to handle control events from 64-bit control types
> by changing the type of the minimum, maximum, step and default_value
> field to __u64
>
> All drivers and frameworks will be using this, and v4l2-ioctl.c would be the
> only place where the old event ioctl and structs are used.
>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
> ---
> Please let me know if there are additional requests for such a new ioctl.
>
> Note that I am using number 104 for the ioctl, but perhaps it would be better to
> use an unused ioctl number like 1 or 3. There are quite a few holes in the
> ioctl numbers. We currently have only 82 ioctls, yet are up to ioctl number 103.
> ---
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 9a920f071ff9..969e775b8c25 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -2303,6 +2303,37 @@ struct v4l2_event {
> __u32 reserved[8];
> };
>
> +struct v4l2_event_ext_ctrl {
> + __u32 changes;
> + __u32 type;
> + union {
> + __s32 value;
> + __s64 value64;
> + };
> + __s64 minimum;
> + __s64 maximum;
> + __s64 step;
> + __s64 default_value;
> + __u32 flags;
> +};
> +
> +struct v4l2_ext_event {
> + __u32 type;
> + __u32 id;
> + union {
> + struct v4l2_event_vsync vsync;
> + struct v4l2_event_ext_ctrl ctrl;
> + struct v4l2_event_frame_sync frame_sync;
> + struct v4l2_event_src_change src_change;
> + struct v4l2_event_motion_det motion_det;
> + __u8 data[64];
> + } u;
If I'd change something in the event IOCTL, I'd probably put the reserved
fields here. That'd allow later taking some for the use of the event data
if needed.
I might also increase the size of the event data. 64 bytes is not that
much. But you indeed end up copying it around all the time... So it's a
trade-off.
> + __u64 timestamp;
> + __u32 pending;
> + __u32 sequence;
> + __u32 reserved[8];
> +};
> +
> #define V4L2_EVENT_SUB_FL_SEND_INITIAL (1 << 0)
> #define V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK (1 << 1)
>
> @@ -2475,6 +2506,7 @@ struct v4l2_create_buffers {
> #define VIDIOC_DBG_G_CHIP_INFO _IOWR('V', 102, struct v4l2_dbg_chip_info)
>
> #define VIDIOC_QUERY_EXT_CTRL _IOWR('V', 103, struct v4l2_query_ext_ctrl)
> +#define VIDIOC_DQEXTEVENT _IOR('V', 104, struct v4l2_ext_event)
How do you plan to name the new buffer handling IOCTLs? I.e. with or
without underscores around "EXT"?
>
> /* Reminder: when adding new ioctls please add support for them to
> drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */
--
Kind regards,
Sakari Ailus
sakari.ailus@xxxxxxxxxxxxxxx
