On Sat, 2009-02-21 at 17:40 +0100, Hans Verkuil wrote:
> On Saturday 21 February 2009 16:48:00 Andy Walls wrote:
> > Hans,
> >
> > I think ivtv's new handling of S_STD for a GPIO mux has a bug.  If the
> > user has a GPIO mux set to Composite 1/Audio Line-in 1, then a
> > VIDIOC_S_STD call will reroute the GPIO audio mux back to the tuner.
> 
> Hmm, yes this is a very, very old bug. It was there from the very beginning. 
> The idea is that when you are in radio mode, then a call to S_STD should 
> switch you back to video mode. 

Yeah.  I got that.

I noted the V4L2 spec said switching inpuits could have side effect, but
not seting the standard once one had switched the input.  The radio mode
abuse of S_STD has a disallowed side effect. :(

Quite a Catch 22 if you have a card with a PAL tuner, with GPIO mux
control, and want to switch the standard to NTSC on line in 1.  (My
exact situation with the Conexant PAL/SECAM card.)

I just wanted to make sure this wasn't anything new.


> So there should be some additional 
> administration here to keep track of the video input and set it back to 
> that, rather than just choosing the tuner input.
> 
> Of course, abusing S_STD for something like this is dubious as well, but it 
> is rather low on the long list of things we can improve.
> 
> To be honest, I don't feel terribly compelled to go in and fix it. I'm a bit 
> too busy lately :-)

Not surprisingly, I've added a FIXME to the cx18 driver code and I am
moving on as well. :)

There is only one well supported card under cx18 that has a GPIO mux
control and it's not widely available.

Regards,
Andy


> Regards,
> 
>       Hans



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