On Tuesday, July 26, 2011 16:38:19 Hans de Goede wrote: > Hi, > > On 07/26/2011 04:19 PM, Hans Verkuil wrote: > > On Tuesday, July 26, 2011 15:51:58 Hans de Goede wrote: > > > > <snip> > > >>> An open question is whether writing to an inactive and volatile control should return > >>> an error or not. > >> > >> I would prefer an error return. > > > > I am worried about backwards compatibility, though. Right now inactive controls > > can be written safely. Suddenly you add the volatile flag and doing the same thing > > causes an error. > > > > Also, a program that saves control values will have to skip any control that: > > > > 1) Is read or write only > > 2) Is inactive and volatile > > > > The first is obvious, but the second not so much. > > > > Another reason for not returning an error is that it makes v4l2-ctrls.c more complex: if > > autogain is on and I call VIDIOC_S_EXT_CTRLS to set autogain to off and gain to a new > > manual value, then it is quite difficult to detect that in this case setting gain is OK > > (since autogain is turned off at the same time). > > > > The more I think about it, the more I think this should just be allowed. The value > > disappears into a black hole, but at least it won't break any apps. > > Ok disappear into a black hole it is :) Good. Then I'll try to work on this this week. Regards, Hans -- 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
