Hi Laurent, On Sat, Sep 1, 2012 at 7:52 PM, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> 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. > two controls I didn't get it ? When we have menu itself with a list of standard patterns why would two controls be required ? Thx, --Prabhakar Lad >> 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. > > -- > Regards, > > Laurent Pinchart > -- 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
