Hello, Not so many time ago i noticed such line in dmesg: radio-mr800 2-1:1.0: Non-NULL drvdata on register Quick review showed that it appears in usb_amradio_probe fucntions. Then i found such code in v4l2_device_register() function (v4l2-device.c file): /* Set name to driver name + device name if it is empty. */ if (!v4l2_dev->name[0]) snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s % s", dev->driver->name, dev_name(dev)); if (dev_get_drvdata(dev)) v4l2_warn(v4l2_dev, "Non-NULL drvdata on register\n"); dev_set_drvdata(dev, v4l2_dev); return 0; The questions is - should i deal with this warning in dmesg? Probably the order of callbacks in radio-mr800 probe function is incorrect. The second questions - should i make atomic_t users counter instead of int users counter? Then i can use atomic_inc(), atomic_dec(), atomic_set(). It helps me to remove lock/unlock_kernel() functions. -- Best regards, Klimov Alexey -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html