OK - this whole thing is starting to get seriously ugly again. So far we have two options: Gerd: 1 registration method, move all responsibility to the driver (very intrusive at all levels). Michael: retain both registration methods (results in overly complex videodev.c). I would like to propose a third method, which may contain the best of both worlds (although it may also be hopelessly impractical): 1) Retain only 1 registration method (Gerd's fops method). 2) Remove all v4l1 compatibility into a separate module. 3) Have the compatibility module register distinct devices for v4l1 compatibily. What will change: 1) v4l1 drivers will not change. 2) v4l2 drivers must do their own userspace copying (probably a single helper function in videodev that v4l2 modules must call). 3) applications will see two devices for every v4l2 device - one the native v4l2 device, and the other a completely separate device registered by the compatibility layer. 4) some sort of a hook will be required in videodev to inform the compatibility layer that a non-v4l1 capable device has just registered. The only disadvantage of this is that we now get two devices (and the consequent user confusion) for every v4l2 device). The main advantage is that it is minimally intrusive, and completely modularises the compatibility layer. Comments? -justin
