The i.MX8 M Plus has a compression curve inside the compand block. This curve is necessary to process HDR stitched data and is useful for other aspects like applying a digital gain to the incoming sensor data. Add a basic algorithm for the compression curve. This algorithm has a hardcoded input width of 20bit and output width of 12bit which matches the imx8mp pipeline. Only a static gain is supported in this version. Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>