https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=277885
> There is an alternative driver (bcm2835_unicam) that is a pure Linux driver for the csi2 receiver. It purely writes the frames to ram and has no ae or awb control loops, but it can easily support any sensor for which there is a Linux driver.

https://www.raspberrypi.org/forums/viewtopic.php?p=1724505#p1724505
> The CPU provides the CSI2 receiver peripheral with the address of the buffer to write to, and it then provides an interrupt at the end of frame.
> Forget the firmware. Use the V4L2 drivers ("dtoverlay=imx477" in config.txt)

https://www.raspberrypi.org/forums/viewtopic.php?p=1789829#p1789829
> The CSI lines meet the MIPI D-PHY spec, so switch voltage based on whether in Low Power (LP) or High Speed (HS) mode.
> OK. Thank you very much. If I am reading what I found correctly, it the LP mode is 1.2V and the HS mode is differential signal swing of a few hundred milivolts. Does that sound about right?
> Also, am I correct in assuming that the clock line signal is generated by the camera module, and is thus an input on the Rasbperry Pi side?
> Yes, all signals within a D-PHY link are in the same direction, from source to sink.