Sakari Ailus wrote: > Hans Verkuil wrote: >> On Tuesday, March 29, 2011 11:35:19 Sakari Ailus wrote: >>> Hi Hans, >>> >>> Many thanks for the comments! >>> > > ... > >>> It occurred to me that an application might want to turn off a flash >>> which has been strobed on software. That can't be done on a single >>> button control. >>> >>> V4L2_CID_FLASH_SHUTDOWN? >>> >>> The application would know the flash strobe is ongoing before it >>> receives a timeout fault. I somehow feel that there should be a control >>> telling that directly. >>> >>> What about using a bool control for the strobe? >> >> It depends: is the strobe signal just a pulse that kicks off the flash, or is >> it active throughout the flash duration? In the latter case a bool makes >> sense, in the first case an extra button control makes sense. > > I like buttons since I associate them with action (like strobing) but on > the other hand buttons don't allow querying the current state. On the > other hand, the current state isn't always determinable, e.g. in the > absence of the interrupt line from the flash controller interrupt pin > (e.g. N900!). Oh, I need to take my words back a bit. There indeed is a way to get the on/off status for the flash, but that involves I2C register access --- when you read the fault registers, you do get the state, even if the interrupt linke is missing from the device. At least I can't see why this wouldn't work, at least on this particular chip. What you can't have in this case is the event. So, in my opinion this suggests that a single boolean control is the way to go. Regards, -- Sakari Ailus sakari.ailus@xxxxxxxxxxxxxxxxxxxxxxxxxx -- 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
