Hi,
while doing LPC examination for keyboard actions on Getac laptop few weeks ago, I noticed that the controlling sequence for backlight step has been put outside of an ACPI spec for no visible reason (therefore it is not possible to control backlight using unmodified ectool, for example).
Sample step control sequence when Fn+Backlightxx is pressed looks like following:
CT DT 0x80 0x17 // Reading 0x17 for current level, twice (why???) 0x80 0x17 0x86 0xff 0xf9 0x7f // Ok, now that`s weird, Why OEM-ing control sequences is necessary in there? 0x80 0x17 // Reading updated value
I wonder if some people in list have touched simular kind of development, is there any real reason behind using non-standard control commands for EC? There *are* counterexamples in coreboot tree, but they are using very extensive control command set and stepping outside of spec looks reasonable. In my case, controller seemingly uses just as few handles as the spec suggests, but omits standard ones in favor of 0x85/0x86, could be there any practical reason for doing this?