[libcamera-devel] [PATCH v2] libcamera: v4l2_device: Workaround faulty control menus

[Kieran Bingham]

Quoting Marian Buschsieweke (2022-11-03 09:42:35)
> Hi,
> 
> On Wed, 2 Nov 2022 21:44:41 +0100
> Marian Buschsieweke <marian.buschsieweke at ovgu.de> wrote:
> 
> > I can test this tomorrow to confirm that exposure_auto cannot be set to any of
> > [0..3], or whether indeed just the labels are missing.
> 
> at least for my K20 device it does indeed not support any of the menu items:
> 
> ~ $ v4l2-ctl --list-devices
> K20 USB CAMERA: K20 USB CAMERA (usb-0000:00:14.0-1):
>         /dev/video2
>         /dev/video3
>         /dev/media1
> 
> Integrated Camera: Integrated C (usb-0000:00:14.0-8):
>         /dev/video0
>         /dev/video1
>         /dev/media0
> 
> ~ $ v4l2-ctl -d /dev/video2 -lL
>                      brightness 0x00980900 (int)    : min=-64 max=64 step=1 default=0 value=0
>                        contrast 0x00980901 (int)    : min=0 max=64 step=1 default=33 value=33
>                      saturation 0x00980902 (int)    : min=0 max=128 step=1 default=64 value=64
>                             hue 0x00980903 (int)    : min=-40 max=40 step=1 default=0 value=0
>  white_balance_temperature_auto 0x0098090c (bool)   : default=1 value=1
>                           gamma 0x00980910 (int)    : min=72 max=500 step=1 default=120 value=120
>                            gain 0x00980913 (int)    : min=0 max=100 step=1 default=0 value=0
>            power_line_frequency 0x00980918 (menu)   : min=0 max=2 default=1 value=1 (50 Hz)
>                                 0: Disabled
>                                 1: 50 Hz
>                                 2: 60 Hz
>       white_balance_temperature 0x0098091a (int)    : min=2800 max=6500 step=1 default=4600 value=4600 flags=inactive
>                       sharpness 0x0098091b (int)    : min=0 max=6 step=1 default=6 value=6
>          backlight_compensation 0x0098091c (int)    : min=0 max=2 step=1 default=1 value=1
>                   exposure_auto 0x009a0901 (menu)   : min=0 max=3 default=0 value=0
>               exposure_absolute 0x009a0902 (int)    : min=1 max=5000 step=1 default=2500 value=2500 flags=inactive
>          exposure_auto_priority 0x009a0903 (bool)   : default=0 value=1
>                  focus_absolute 0x009a090a (int)    : min=1 max=1023 step=1 default=1 value=230 flags=inactive
>                      focus_auto 0x009a090c (bool)   : default=1 value=1
> ~ $ v4l2-ctl -d /dev/video2 -c exposure_auto=0
> VIDIOC_S_EXT_CTRLS: failed: Invalid argument
> Error setting controls: Invalid argument
> ~ $ v4l2-ctl -d /dev/video2 -c exposure_auto=1
> VIDIOC_S_EXT_CTRLS: failed: Invalid argument
> Error setting controls: Invalid argument
> ~ $ v4l2-ctl -d /dev/video2 -c exposure_auto=2
> VIDIOC_S_EXT_CTRLS: failed: Invalid argument
> Error setting controls: Invalid argument
> ~ $ v4l2-ctl -d /dev/video2 -c exposure_auto=3
> VIDIOC_S_EXT_CTRLS: failed: Invalid argument
> Error setting controls: Invalid argument

Ok - so that makes me believe we're indeed better off returning
ControlInfo();

That will require a bit more work to fix the upper layer so that it
correctly skips controls that are returned as empty - but actually
looking at the code - that's already something we need to do.

Higher in the function there is the statement:

         if (ctrl.minimum < 0)
                return ControlInfo();

Which I expect will crash in the caller right now, as we discovered.

So lets drop this version of the patch and fix things up to be able to
return ControlInfo(); when indicies are empty - and make sure the higher
layers realise this and do not add the control.
--
Kieran


> 
> Kind regards,
> Marian