Patents is often a concern. Maybe you think you're not violating any patents. But somebody with access to your code could find something that looks like a viola

Patents is often a concern. Maybe you think you're not violating any patents. But somebody with access to your code could find something that looks like a violation. Real or not, it can spell trouble for you. Your code delivery could also contain parts that are licensed from other companies, limiting your options with regards to licensing. One way to limit the problem is to put most of your "secret sauce" code onto one or more sub-processors embedded in the imaging hardware. The register bank of your hardware would only be accessible to these sub-processors, meaning that you don't have to publish your register definitions. Then you can deliver the sub-processor microcode as a binary blob (independent of the host OS) and let the kernel module itself be open-source. This approach is taken by at least some vendors.