On Wednesday, June 29, 2011 12:30:26 Laurent Pinchart wrote:
> Hi Hans,
>
> On Wednesday 29 June 2011 12:06:57 Hans Verkuil wrote:
> > > On Tuesday 28 June 2011 17:18:07 Hans Verkuil wrote:
> > >> Originally no control events would go to the filehandle that called the
> > >> VIDIOC_S_CTRL/VIDIOC_S_EXT_CTRLS ioctls. This was to prevent a feedback
> > >> loop.
> > >>
> > >> This is now only done if the new V4L2_EVENT_SUB_FL_NO_FEEDBACK flag is
> > >> set.
> > >
> > > What about doing it the other way around ? Most applications won't want
> > > that feedback, you could disable it by default.
> >
> > I thought about that, but that's harder to explain since that flag would
> > then suppress an exception to the normal handling of event.
> >
> > It's easier to say: events are sent to everyone, but if you set this flag,
> > then we make this exception.
>
> Events are sent to everyone but you, but if you set this flag, you get them
as
> well.
I thought about it a bit more, and a better reason for changing this to
ALLOW_FEEDBACK is that it forces you to think about the consequences of
setting this flag.
I'll change it.
Regards,
Hans
> It's not that hard ;-)
>
> > I suspect that most applications do not need to set this flag anyway, only
> > applications like qv4l2 that create a control panel need it.
>
> Most applications won't need events for controls they modify themselves.
While
> this might not break them, it would still be a waste of resources.
>
> --
> Regards,
>
> Laurent Pinchart
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