Re: Chroma gain configuration

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Devin Heitmueller wrote:
> On Mon, Feb 22, 2010 at 8:40 AM, Mauro Carvalho Chehab
> <mchehab@redhat.com> wrote:
>> I think that the control you want is V4L2_CID_GAIN.
> 
> I would have guessed the CID_GAIN control would have been responsible
> for *luma* gain.  I could be wrong about that of course (but that is
> what I believe people typically think of when they think of "gain" in
> general).

Maybe it is for luma, but I bet that this is also is used for more than one
different kind of control. We should revisit those controls and properly
specify what they should do.
> 
>>> I believe there probably are cases where extended controls are required,
>>> but I believe just a general user control based on
>>> V4L2_CID_PRIVATE_BASE should probably be able to work even with the
>>> generic VIDIOC_S_CTRL
>>>
>>> I'm just asking because it would mean in order for v4l2-dbg to work
>>> with my solution i would have to add support for extended controls in
>>> general to the saa7115 driver, which shouldn't be necessary.
>> The end objective is to have everybody implementing extended controls and
>> removing the old controls, letting the V4L2 ioctl2 to convert a call to a
>> simple control into an extended control callback. So, I think it would
>> be worthy to implement extended control on saa7115.
> 
> Ok then.  I'll add the 15-20 lines of code which add the extended
> controls mechanism to the 7115, which just operates as a passthrough
> for the older control interface.

The better is to do the opposite: extended being the control interface and
the old calls as a passthrough, since the idea is to remove the old interface
after having all drivers converted.

-- 

Cheers,
Mauro