> For example v4l2 has an ioctl to send raw read/write commands to a camera module. Having a datasheet one can then check which registers do what and one can se

> For example v4l2 has an ioctl to send raw read/write commands to a camera module. Having a datasheet one can then check which registers do what and one can set various features, but this requires using different registers and values for different camera modules. That touches a nerve. I worked on an embedded system which used one of these camera modules and the datasheet was probably accurate at some point in time during the development of the module, but clearly as the module was developed the data sheet did not keep up. Eventually it was necessary to employ a bus sniffer to capture all traffic between a demonstration kit and module and reproduce the streams byte for byte to get the camera to do what was needed. It was clear from the streams that the demonstration code was using device registers not described in the data sheet. I suppose that a big customer for the module (such as a cell phone manufacturer) would get access to an engineer who could provide the necessary information, but that was not us. > ... has been quite difficult on various embedded devices. Agreed.