On Sat September 1 2012 16:22:30 Laurent Pinchart wrote:
> Hi Sakari,
>
> On Saturday 01 September 2012 12:57:07 Sakari Ailus wrote:
> > On Wed, Aug 29, 2012 at 08:11:50PM +0530, Prabhakar Lad wrote:
>
> [snip]
>
> > > For test pattern you meant control to enable/disable it ?
> >
> > There are two approaches I can think of.
> >
> > One is a menu control which can be used to choose the test pattern (or
> > disable it). The control could be standardised but the menu items would have
> > to be hardware-specific since the test patterns themselves are not
> > standardised.
>
> Agreed. The test patterns themselves are highly hardware-specific.
>
> From personal experience with sensors, most devices implement a small, fixed
> set of test patterns that can be exposed through a menu control. However,
> some
> devices also implement more "configurable" test patterns. For instance the
> MT9V032 can generate horizontal, vertical or diagonal test patterns, or a
> uniform grey test pattern with a user-configurable value. This would then
> require two controls.
>
> > The alternative is to have a boolean control to enable (and disable) the
> > test pattern and then a menu control to choose which one to use. Using or
> > implemeting the control to select the test pattern isn't even strictly
> > necessary to get a test pattern out of the device: one can enable it without
> > knowing which one it is.
> >
> > So which one would be better? Similar cases include V4L2_CID_SCENE_MODE
> > which is used to choose the scene mode from a list of alternatives. The main
> > difference to this case is that the menu items of the scene mode control
> > are standardised, too.
> >
> > I'd be inclined to have a single menu control, even if the other menu items
> > will be device-specific. The first value (0) still has to be documented to
> > mean the test pattern is disabled.
> >
> > Laurent, Hans: what do you think?
>
> A menu control with value 0 meaning test pattern disabled has my preference
> as
> well.
+1
Hans
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