> > call call_fext_func() with a NULL device. Let's just skip those > > function calls when the FUJ02E3 device is not present. > > > > Interesting. We call call_fext_func from many locations using the > "device" argument, or the driver static "fext". > > This looks to me that we should be a bit more consistent here. This is intentional. The plan was to extract the backlight part of fujitsu-laptop into a separate module, fujitsu-backlight, which would use a simple two-function API exposed by fujitsu-laptop to control LCD backlight power. Those functions would have to somehow access the FUJ02E3 ACPI device while not being ACPI callbacks. Thus, fext is storing a pointer to the last (and most likely only) instantiated FUJ02E3 ACPI device so that it can be used for setting LCD backlight power from fujitsu-backlight. See commit ca0d9eab0fb5 for a brief discussion of why this solution was chosen. > Finally, it seems a proper fix would be to either not register the > backlight device if !fext or to check for !fext inside call_fext_func. My draft patch series which splits off fujitsu-backlight includes the NULL check for fext inside the functions exposed by fujitsu-laptop. Sadly, I have not got round to submitting it yet. Just to make sure we are all on the same page here, please note that access to FUJ02E3 is only needed for controlling LCD backlight _power_, not LCD backlight _brightness_. Speaking of which, I just noticed that my S7020 can control its LCD brightness just fine without fujitsu-laptop being loaded. Heck, it even works when booted with "noacpi". It seems to me that on this model, LCD brightness control works at the firmware level and an ACPI-based driver is just another possible way of getting/setting LCD brightness level. Jonathan, IIRC you have an S7020 as well, could you please test that? You know better than me why this driver was needed in the first place. Ville, could you please test your S6120 for the above as well? Please try unloading/blacklisting fujitsu-laptop and see whether LCD backlight control still works. Finally, it seems the S6120 also has a row of "application panel" hotkeys above the keyboard, but lacks the FUJ02E3 ACPI device, so I am wondering whether these hotkeys work in Linux. Ville, do they? In fact, it would be super helpful if you could post acpidumps from all three models you have access to (you mentioned S6120, S6010 and S7110). IMHO the biggest issue we have had while refactoring fujitsu-laptop is a narrow set of known/tested models. -- Best regards, Michał Kępień
