On Friday, February 04, 2011 13:03:13 Sakari Ailus wrote:
> Hi Hans,
>
> Thanks for the comments!
>
> Hans Verkuil wrote:
> ...
> >> @@ -424,6 +430,8 @@ struct v4l2_subdev_ops {
> >> #define V4L2_SUBDEV_FL_IS_SPI (1U << 1)
> >> /* Set this flag if this subdev needs a device node. */
> >> #define V4L2_SUBDEV_FL_HAS_DEVNODE (1U << 2)
> >> +/* Set this flag if this subdev generates events. */
> >> +#define V4L2_SUBDEV_FL_HAS_EVENTS (1U << 3)
> >
> > Do we need this flag...
> >
> >>
> >> /* Each instance of a subdev driver should create this struct, either
> >> stand-alone or embedded in a larger struct.
> >> @@ -446,6 +454,8 @@ struct v4l2_subdev {
> >> /* subdev device node */
> >> struct video_device devnode;
> >> unsigned int initialized;
> >> + /* number of events to be allocated on open */
> >> + unsigned int nevents;
> >
> > ...when we have this field? We could just test whether nevents > 0.
>
> Not necessarily. But:
>
> - It's easy to check whether events are expected to be supported by the
> driver using the flag and
Testing sd->nevents is even easier, but...
> - AFAIR it was agreed that as the driver is free to allocate more events
> using v4l2_event_alloc(), it may choose not to allocate any at
> initialisation but e.g. do it in in VIDIOC_SUBSCRIBE_EVENT only.
...this is a good point. So let's keep the flag.
Regards,
Hans
>
> What do you think?
>
>
--
Hans Verkuil - video4linux developer - sponsored by Cisco
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