mchehab: Bom dia!
If I have three integer controlls (A, B and C) which are related with a constraint, A <= B <= C. Can I in .s_ctrl for B adjust the values of A or C to match this constraint if B is updated or should I block changeing B to a value which would break the constraint in .try_ctrl and .s_ctrl?
neg: good question
we're missing Hans :-)
I have tried option 2, to block changes that break the constraint, but it becomes a PITA to use the controlls then :-)
you should group them all in a cluster so that they can be changed in one go
neg: You need __v4l2_ctrl_modify_range().
Or perhaps it'd be better to just use __v4l2_ctrl_s_ctrl() in order to avoid enforcing a strict order of changing the controls, unless you especially want that.
The smiapp driver uses __v4l2_ctrl_modify_range() to change the value range for the exposure based on the vertical blanking control.
sailus: I don't think we want to modify the range of the other two controls every time we change one of them
that would be messy
pinchartl: Depends on what the controls are for.
If it's something that we want to ensure the user takes an informed decision to change, perhaps yes.
Otherwise it can be just changed, as simple as that.
sailus: I think it's boundaries for histogram buckets
yes it's boundaries for a histogram
pinchartl: how ever could you guess :-)
:-)
do you have 3 controls only ? don't we have 6 buckets ?
yes it's 12 controlls in total, 6 buckets and each have a lower and upper value
example of 3 since each control bondary only depends on the value of its neighbors
I wonder whether it wouldn't make more sense to create a single array control
with 12 values
pinchartl: using v4l2_ctrl_cluster() ?
neg: no, using a compound control
neat, it's the way to go. Did not know they exsisted :-)
average linux user seeking support regarding v4l, did I come to the right place?
sure
v4l2-ctl does not show all controls for a HVR-1900. I can change it using sysfs (bitrate for example) but not using v4l2. Is this normal behaviour?
tried arch linux and raspian
Driver Info (not using libv4l2):
 Driver name   : pvrusb2
 Card type     : WinTV HVR-1900 Model 73xxx
 Bus info      : usb-20980000.usb-1.3
 Driver version: 4.4.13
hverkuil, anything new in request API after meeting?