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 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
