Hello,
On Wed, Feb 20, 2019 at 03:34:44PM +0200, Sakari Ailus wrote:
> On Tue, Feb 05, 2019 at 02:49:45PM +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>
> > ---
> > I chose to name this DQ_EXT_EVENT since the struct it dequeues is now called
> > v4l2_ext_event. This is also consistent with the names of the G/S/TRY_EXT_CTRLS
> > ioctls. An alternative could be VIDIOC_DQEXT_EVENT as that would be consistent
> > with the lack of _ between DQ and EVENT in the current ioctl. But somehow it
> > doesn't look right.
> >
> > Changes since v1:
> > - rename ioctl from VIDIOC_DQEXTEVENT.
> > - move the reserved array up to right after the union: this will allow us to
> > extend the union into the reserved array if we ever need more than 64 bytes
> > for the event payload (suggested by Sakari).
> > ---
> > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> > index 9a920f071ff9..301e3678bdb0 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;
> > + __u32 reserved[8];
> > + __u64 timestamp;
> > + __u32 pending;
> > + __u32 sequence;
> > +};
>
> The size of the struct is at the moment 120 bytes. The allocation done by
> the kernel is always 128 bytes anyway, and the ext control event above is
> just 12 bytes short of the maximum. I'd therefore add two more reserved
> fields. That's fine tuning though. The structs look very nice to me.
>
> Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
This looks fine to me too.
> > +
> > #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_DQ_EXT_EVENT _IOR('V', 104, struct v4l2_ext_event)
> >
> > /* Reminder: when adding new ioctls please add support for them to
> > drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */
--
Regards,
Laurent Pinchart
