On Wed, Jun 25, 2014 at 2:54 AM, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > Hi Pawel, > > On Wednesday 25 June 2014 11:46:24 Pawel Osciak wrote: >> On Tue, Jun 17, 2014 at 11:45 PM, Vincent Palatin wrote: >> > Map V4L2_CID_TILT_RELATIVE and V4L2_CID_PAN_RELATIVE to the standard UVC >> > CT_PANTILT_RELATIVE_CONTROL terminal control request. >> > >> > Tested by plugging a Logitech ConferenceCam C3000e USB camera >> > and controlling pan/tilt from the userspace using the VIDIOC_S_CTRL ioctl. >> > Verified that it can pan and tilt at the same time in both directions. >> > >> > Signed-off-by: Vincent Palatin <vpalatin@xxxxxxxxxxxx> >> > >> > Change-Id: I7b70b228e5c0126683f5f0be34ffd2807f5783dc >> > --- >> > >> > Changes >> > v2: fix control request name in description. >> >> The patch looks good, but I have a more general comment for everyone to >> consider. This doesn't match the expected functionality of >> controls V4L2_CID_PAN/TILT_RELATIVE. This is basically an on/off switch for >> pan/tilt, which once enabled will keep going until turned off (or I'm >> guessing until the maximum pan/tilt is reached), while the controls are >> supposed to expose an ability to turn the camera by a specified amount. >> Here the amount will also be ignored... > > I agree with you here, and this mismatch between the V4L and UVC controls is > the reason why I haven't implemented relative pan/tilt support. > >> Given that this is a standard UVC control, perhaps we need new V4L2 >> controls for it, as I'm assuming we can't change the meaning of existing >> controls? > > We could extend the meaning of the controls to cover the UVC behaviour in a > device-specific fashion, but that would be confusing for applications, so new > controls might be a better idea. Ok, I will add another patch to create new V4L2_CID_PAN_SPEED / V4L2_CID_TILT_SPEED controls. -- Vincent -- 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
