Re: Chroma gain configuration

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

Devin Heitmueller wrote:
> On Mon, Feb 22, 2010 at 8:58 AM, Mauro Carvalho Chehab
> <mchehab@redhat.com> wrote:
>>> 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.
> 
> I gave this a bit of thought, and I'm not sure what you are proposing
> is actually possible.  Because the extended controls provides a
> superset of the functionality of the older user controls interface, it
> is possible to create a extended control callback which just passes
> through the request (since any user control can be converted into a
> extended control).  However, you cannot convert the extended control
> results into the older user control format, since not all the
> information could be provided.
> 
> In fact, I would be in favor of taking the basic logic found in
> cx18_g_ext_ctrls(), and making that generic to the videodev interface,
> such that any driver which provides a user control interface but
> doesn't provide an extended control function will work if the calling
> application makes an extended control call.  This will allow userland
> applications to always use the extended controls API, even if the
> driver didn't explicitly add support for it.

That's exactly the idea: convert all driverst o use ext_ctrl's and let the
V4L2 core to handle the calls to the non-extended interface. 


-- 

Cheers,
Mauro