On Wed 6 March 2013 11:11:24 volok...@gmail.com wrote:
> On Wed, Mar 06, 2013 at 11:02:47AM +0100, Hans Verkuil wrote:
> > On Wed 6 March 2013 10:48:13 volok...@gmail.com wrote:
> > > Hi,
> > > Hans
> > >
> > > I found in d8077d2df184f3ef63ed9ff4579d41ca64e12855 commit,
> > > that V4L2_CTRL_FLAG_VOLATILE flag was disabled for some STD controls
> > > and fully disabled g_ctrl iface. So How can userspace know about changing
> > > some values?
> >
> > VOLATILE is used when register values can change automatically (e.g. if
> > autogain is on and the device regulates the gain and updates that gain
> > register itself).
> >
> Right that!!!
> there one register for all 4 channell for each of
> AUTOGAIN,CHROMA,RED_B,BLUE_B reg, so if one channel changes CHROMA value (it
> changes all 4 channels),
> the another channel will have cached old value, instead new (case it value
> have not volatile control)
Ah, yes. Good point. I need to modify the code to have two control handlers:
one for the global controls and one for the channel controls. That's the right
way to do this. I'll implement that later this week.
Regards,
Hans
> > However, testing proved that the hardware doesn't update anything when
> > in autogain mode, hence volatile support isn't needed.
> >
> > Note that the control framework always caches the last control value,
> > so to get non-volatile controls the framework just returns that cached
> > value.
> >
> > Regards,
> >
> > Hans
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