ACPI: thinkpad-acpi: support 16 levels of brightness (v3)
commit5ddf5f912cec3eab2fba5fc8925195a3a9226c99
authorHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Thu, 11 Oct 2007 07:10:14 +0000 (11 04:10 -0300)
committerHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Tue, 26 Feb 2008 02:34:05 +0000 (25 23:34 -0300)
tree2b97099359701f519e206039284882dd7d02deeb
parent94e7f24c66a78ba889d3c8358013bc190af96d26
ACPI: thinkpad-acpi: support 16 levels of brightness (v3)

Lenovo ThinkPads often have 16 brightness levels in EC, and not just eight
levels like older ThinkPads.  They also have standard ACPI backlight
brightness control.

We detect the number of brightness levels by the presence of a BCLL package
with 16 entries.  If BCLL is not there, we assume eight levels (Z6*).  If
it is there, but it doesn't have 16 entries, we assume eight levels (T60).
Otherwise we assume sixteen levels (T61, X61, etc).

We don't use _BCL because it can have side-effects in thinkpads.  Thanks to
Thomas Renninger <trenn@suse.de> for notifying me of this potential
problem.

Using the standard ACPI backlight brightness control *instead* of the
native thinkpad backlight control is a better idea, though.  A different
patch will take care of this.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Thomas Renninger <trenn@suse.de>
Documentation/thinkpad-acpi.txt
drivers/misc/thinkpad_acpi.c
drivers/misc/thinkpad_acpi.h