设置曝光、gain等control

通过命令列出IMX219可控制的control（注意下方IMX219对应的节点是/dev/v4l-subev10）。

# v4l2-ctl -d /dev/v4l-subdev10 -l

User Controls

                       exposure 0x00980911 (int)    : min=4 max=1759 step=1 default=1600 value=1600
                horizontal_flip 0x00980914 (bool)   : default=0 value=0 flags=modify-layout
                  vertical_flip 0x00980915 (bool)   : default=0 value=0 flags=modify-layout

Camera Controls

             camera_orientation 0x009a0922 (menu)   : min=0 max=2 default=1 value=1 (Back) flags=read-only
         camera_sensor_rotation 0x009a0923 (int)    : min=0 max=0 step=1 default=0 value=0 flags=read-only

Image Source Controls

              vertical_blanking 0x009e0901 (int)    : min=4 max=64455 step=1 default=683 value=683
            horizontal_blanking 0x009e0902 (int)    : min=1528 max=1528 step=1 default=1528 value=1528 flags=read-only
                  analogue_gain 0x009e0903 (int)    : min=0 max=232 step=1 default=208 value=208
                red_pixel_value 0x009e0904 (int)    : min=0 max=1023 step=1 default=1023 value=1023
          green_red_pixel_value 0x009e0905 (int)    : min=0 max=1023 step=1 default=1023 value=1023
               blue_pixel_value 0x009e0906 (int)    : min=0 max=1023 step=1 default=1023 value=1023
         green_blue_pixel_value 0x009e0907 (int)    : min=0 max=1023 step=1 default=1023 value=1023

Image Processing Controls

                 link_frequency 0x009f0901 (intmenu): min=0 max=0 default=0 value=0 (456000000 0x1b2e0200) flags=read-only
                     pixel_rate 0x009f0902 (int64)  : min=182400000 max=182400000 step=1 default=182400000 value=182400000 flags=read-only
                   test_pattern 0x009f0903 (menu)   : min=0 max=4 default=0 value=0 (Disabled)
                   digital_gain 0x009f0905 (int)    : min=256 max=4095 step=1 default=256 value=256

用v4l2-ctl可以修改这些control，如修改exposure及analogue_gain，如下：

v4l2-ctl -d /dev/v4l-subdev10  --set-ctrl 'exposure=1216,analogue_gain=10'