On Monday 22 February 2010 22:38:56 Devin Heitmueller wrote: > On Mon, Feb 22, 2010 at 4:32 PM, Mauro Carvalho Chehab > <mchehab@xxxxxxxxxx> wrote: > > Devin Heitmueller wrote: > >> 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. > > I think you actually missed the point of what I'm trying to say: You > can only do the opposite of what you proposed: You can have the v4l2 > core receive extended interface calls and pass those calls through to > the older interface in drivers (since the older interface is a > *subset* of the newer interface). However, you cannot provide a way > for callers of the older interface have those requests passed through > to the new interface (since the old interface does not support > multiple controls in one call and there are multiple classes of > controls in the newer interface). > > In other words, a caller using the extended interface can > automatically call the old interface, but a caller using the old > interface cannot automatically call into the extended interface. Sure you can. See v4l2-ioctl.c, VIDIOC_G/S_CTRL. That's exactly what is being done there. It's the other way around that is not in general possible. Regards, Hans -- Hans Verkuil - video4linux developer - sponsored by TANDBERG -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
