On Sat, Jun 03, 2017 at 09:46:36PM -0700, Steve Longerbeam wrote: > > > On 06/03/2017 02:57 PM, Sakari Ailus wrote: > >On Sat, Jun 03, 2017 at 09:51:39PM +0200, Pavel Machek wrote: > >>Hi! > >> > >>>>>>+ /* Auto/manual exposure */ > >>>>>>+ ctrls->auto_exp = v4l2_ctrl_new_std_menu(hdl, ops, > >>>>>>+ V4L2_CID_EXPOSURE_AUTO, > >>>>>>+ V4L2_EXPOSURE_MANUAL, > >>>>>>0, > >>>>>>+ V4L2_EXPOSURE_AUTO); > >>>>>>+ ctrls->exposure = v4l2_ctrl_new_std(hdl, ops, > >>>>>>+ V4L2_CID_EXPOSURE_ABSOLUTE, > >>>>>>+ 0, 65535, 1, 0); > >>>>> > >>>>>Is exposure_absolute supposed to be in microseconds...? > >>>> > >>>>Yes. > >>> > >>>According to the docs V4L2_CID_EXPOSURE_ABSOLUTE is in 100 usec units. > >>> > >>> OTOH V4L2_CID_EXPOSURE has no defined unit, so it's a better fit IMO. > >>>>Way more drivers appear to be using EXPOSURE than EXPOSURE_ABSOLUTE, too. > >>> > >>>Done, switched to V4L2_CID_EXPOSURE. It's true, this control is not > >>>taking 100 usec units, so unit-less is better. > >> > >>Thanks. If you know the units, it would be of course better to use > >>right units... > > > >Steve: what's the unit in this case? Is it lines or something else? > > Yes, the register interface for exposure takes lines*16. > > Maybe converting from seconds to lines is as simple as > framerate * height * seconds. But I'm not sure about that.
The smiapp and a few other drivers are using lines. One option could be to use lines as the unit and have step as 16. Then the hblank + vblank controls will be needed, too, to enable the user to at least figure out the conversion to Si units. -- Sakari Ailus e-mail: sakari.ai...@iki.fi XMPP: sai...@retiisi.org.uk
