I am sorry for the late reply.
@ryuu, you are right. The title suggests what you seem to be hoping to find. I need to change it to better reflect what was actually achieved in this thread, but I do not see a button to do it at the moment. This thread is actually about finding the right place to pass on brightness control parameters to the kernel. What the kernel does with them once they correctly appear in its command line call is another issue.
It appears to me that even if the parameters are passed on to the kernel correctly, they have no effect. I thought that it might be a missing driver issue, which is why I opened another thread: