Disabling add-ons in the presence of a generic control device

[Bill Nottingham]

Matthew Garrett (mjg59 at srcf.ucam.org) said: 
> We currently have backlight control addons for a couple of systems 
> (Apple and Dell spring to mind). Over time, these platforms are gaining 
> kernel support for the backlight control - either through the vendor 
> adding generic ACPI video support or through hardware specific drivers 
> being written. I'm not quite clear on the cleanest way of doing this 
> with the fdi format, though. It needs to handle two cases:
> 
> 1) The kernel driver is loaded before hal. The addon needs to never be 
> started in this case.
> 2) The kernel driver is loaded after hal. The addon needs to be stopped.
> 
> Anyone have any thoughts on the best way to achieve this?

Is #2 really a case that needs handled? Platform backlight control
isn't something that gets hotplugged post-boot, and modules are
generally all loaded before HAL starts.

Bill