Re: v4l2 ioctls

[Hans Verkuil <hverkuil@xs4all.nl>]

On 09/13/2014 02:37 AM, Shuah Khan wrote:
> Mauro/Hans,
> 
> Thanks for both for your replies. I finally have it working with
> the following:
> 
> S_INPUT
> S_OUTPUT

S_OUTPUT is not necessary. It will never be used in combination with a
modulator since we don't support TV modulators at all.

> S_MODULATOR

I think this is unnecessary as well: we only have radio modulators and
those are always stand-alone drivers.

> S_TUNER
> S_STD
> S_FREQUENCY
> S_HW_FREQ_SEEK
> S_FMT
>  - get tuner in shared mode and hold it
>  - i.e return with tuner held
> 
> STREAMON
>  - get tuner in shared mode and hold it
>  - i.e return with tuner held
> STREAMOFF
>  - put tuner (get is done in STREAMON)

I wouldn't do this. Once you start streaming you hold the tuner and it
isn't released until the filehandle closes. The V4L2 API doesn't have
an explicit 'release tuner' ioctl.

> 
> QUERYSTD
> G_TUNER (au0828 does tuner init in its g_tuner ops)
>  - get tuner in shared mode and hold it

Note that G_TUNER should still work if it can't get hold of the tuner.
I.e., it should never return an error.

>  - service request
>  - put tuner
> 
> With these changes now I have digital stream not get
> disrupted as soon as xawtv starts. I am working through
> issues related to unbalanced nature of tuner holds in
> analog mode.

Nice!

Regards,

	Hans