Re: [RFC PATCH] Add support for V4L2_EVENT_SUB_FL_NO_FEEDBACK

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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.

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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