> Regarding ACPI case and device presents you may assume it if you just call > acpi_walk_namespace() (AFAIU) and check _STA for the device if it's in > the table. > > So, at any point you may have got understanding if device is present > or not, and if it's active or not. Thank you for the tip, though I am a bit confused, sorry. I infer the above is a response to this part of my message: > > On the other hand, registering the platform device before the ACPI > > driver is also incorrect due to reasons I already pointed out in > > another thread (in short: we cannot _assume_ FUJ02E3 is present). Perhaps my wording was inaccurate, but I do not have a technical problem with detecting an ACPI device. Instead, this passage was meant to be a reference to the fourth paragraph of my cover letter for the series titled "fujitsu_init() cleanup", i.e. the lengthy one awaiting comments from you and/or Darren. For your convenience, here is the paragraph in question (roughly the second half is relevant): > That would leave us with the remaining three sysfs attributes of the > platform device, namely dock, lid and radios. These all depend on the > FUJ02E3 ACPI device. Which begs the question: shall we reassign them to > that ACPI device and drop the platform device altogether? This would > logically be the correct thing to do (panasonic-laptop and toshiba_acpi > already assign extra sysfs attributes to ACPI nodes). But I understand > that this would break an 8-year-old userspace interface as functions > previously exposed through /sys/devices/platform/fujitsu-laptop would be > moved to /sys/bus/acpi/devices/FUJ02E3:00. If that is unacceptable, the > least we can (and should) do is to move platform device registration to > acpi_fujitsu_hotkey_add(). What the driver currently does may create > confusion in the future, because the platform device is registered > unconditionally while it clearly depends on FUJ02E3 being present. I do > not know whether FUJ02E3 is present on all Fujitsu devices today without > exception, but I do know that if Fujitsu ever decides to drop that > device from its firmware, we would again (see above) expose a userspace > interface (dock, lid, radios) which simply will not be able to function > properly. Perhaps things will become a bit more clear once you dig through that thread :) -- Best regards, Michał Kępień
