The driver will fail to detect BIOSes that both lack the "ThinkPad" string in the DMI tables, and the EC version string, for ThinkPads that have the EC version string on the most up-to-date BIOSES.
This causes the driver to return -ENODEV, and the module will not load.
The problem can be worked around by giving the module the "force_load=1" parameter.
Problem tracked down to the quirk tables used as a fallback for known-BIOS detection, they would not match if the EC version is flagged as "unknown".
Created attachment 23770 [details]
Fix the detection of T23 and other thinkpads
Fix the quirk tables to also match on BIOSes that miss the EC fw string.
Waiting a day for possible confirmation from bug reporter that the patch works...
From which earlier kernel version is this a regression?
This problem did not appear in the 2.6.31 series (I am quite certain about 188.8.131.52), and hmh's patch fixes it for me. (I am the initial bug reporter.)
Henrique, please cc me on the formal patch email?
Handled-By : Henrique de Moraes Holschuh <firstname.lastname@example.org>
Patch : http://bugzilla.kernel.org/attachment.cgi?id=23770
(In reply to comment #5)
> Henrique, please cc me on the formal patch email?
Will do. I am adding the tested-by and cc lines now, and will ship it to Len Brown in a few minutes. If you'd rather send it to Linus yourself, feel free to do so :)
applied to acpi tree for 2.6.32
thinkpad-acpi: fix detection of old ThinkPads
shipped in linux 2.6.32
But it wasn't tagged email@example.com, so it won't be fixed in 2.6.31.x?
2.6.31 doesn't have the bug, AFAIK.