On Tue March 12 2013 07:56:25 Hans Verkuil wrote: > Hi Sylwester, > > On Wed January 23 2013 23:21:57 Sylwester Nawrocki wrote: > > This patch adds a helper function that allows to modify range, > > i.e. minimum, maximum, step and default value of a v4l2 control, > > after the control has been created and initialized. This is helpful > > in situations when range of a control depends on user configurable > > parameters, e.g. camera sensor absolute exposure time depending on > > an output image resolution and frame rate. > > > > v4l2_ctrl_modify_range() function allows to modify range of an > > INTEGER, BOOL, MENU, INTEGER_MENU and BITMASK type controls. > > > > Based on a patch from Hans Verkuil http://patchwork.linuxtv.org/patch/8654. > > > > Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@xxxxxxxxx> > > Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > I've been playing around with this a bit, using this vivi patch: > > diff --git a/drivers/media/platform/vivi.c b/drivers/media/platform/vivi.c > index c46d2e8..85bc314 100644 > --- a/drivers/media/platform/vivi.c > +++ b/drivers/media/platform/vivi.c > @@ -1093,6 +1093,15 @@ static int vidioc_s_input(struct file *file, void *priv, unsigned int i) > return 0; > > dev->input = i; > + /* > + * Modify the brightness range depending on the input. > + * This makes it easy to use vivi to test if applications can > + * handle control range modifications and is also how this is > + * typically used in practice as different inputs may be hooked > + * up to different receivers with different control ranges. > + */ > + v4l2_ctrl_modify_range(dev->brightness, > + 128 * i, 255 + 128 * i, 1, 127 + 128 * i); > precalculate_bars(dev); > precalculate_line(dev); > return 0; > > And it made me wonder if it wouldn't be more sensible if modify_range would > also update the current value to the new default value? Actually, thinking about it some more, I believe that modify_range should actually include the new control value as argument. That way the caller can decide what to do: use the current value (which then might be clamped), use the default_value or use a remembered previous value. If you agree with this, then I'll make a patch for it. I just need to know what the only user of this call (ov9650.c) should do. I suspect it should use the default value as the new value, but I'm not certain. Regards, Hans > You get weird effects otherwise where the new value is clamped to either > the minimum or maximum value if the current value falls outside the new > range. > > Regards, > > Hans > > PS: qv4l2 has been updated to support range update events. > -- 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
