Extern or forward variable declaration at include/media/v4l2-subdev.h, line 788 References: drivers/media/i2c/dw9768.c, line 102 drivers/media/i2c/imx214.c, line 52 drivers/media/i2c/imx219.c, line 547 drivers/media/i2c/imx290.c, line 77 drivers/media/i2c/m5mols/m5mols_core.c, line 36 drivers/media/i2c/mt9p031.c, line 129 drivers/media/i2c/mt9t001.c, line 120 drivers/media/i2c/noon010pc30.c, line 132 drivers/media/i2c/ov2680.c, line 109 drivers/media/i2c/ov2685.c, line 87 drivers/media/i2c/ov5640.c, line 229 drivers/media/i2c/ov5645.c, line 97 drivers/media/i2c/ov5695.c, line 99 drivers/media/i2c/ov8856.c, line 593 drivers/media/i2c/s5c73m3/s5c73m3.h, line 385 drivers/media/i2c/s5k4ecgx.c, line 192 drivers/media/i2c/s5k5baf.c, line 291 drivers/media/i2c/s5k6a3.c, line 61 drivers/media/i2c/s5k6aa.c, line 234 drivers/media/i2c/st-mipid02.c, line 85 drivers/media/i2c/tda1997x.c, line 227 drivers/media/platform/exynos4-is/mipi-csis.c, line 208 include/media/v4l2-subdev.h, line 788 include/media/v4l2-subdev.h, line 798