[libcamera-devel] conflicting default control values

[Christian Rauch]

Hello,

When using the V4L2 interface, I noticed that configuration values will
stay set globally even after the process that set them exits. E.g.
setting a low exposure value via libcamera and quitting the process will
keep that exposure value such that other processes, such as skype or
guvcview, will show the images with the same setting (e.g. low
exposure). This is quite inconvenient as some programs will not be able
to reset those values.

I worked around this issue by resetting these parameters to the default
values defined in libcamera. During this, I also noticed that the set of
default values might collide. On my system, when reading and setting the
default control values, the auto-exposure will be activated and a
specific exposure time will be set. This causes errors in the driver and
all requests will be cancelled until the auto-exposure is set to false
or the auto-exposure is removed.

Is there a way for libcamera to either reset the V4L2 settings to the
initial condition or to prevent conflicting control values?

Best,
Christian