[ltp] tpacpi bug in tpacpi::thinklight/brightness for X1 Carbon

Henrique de Moraes Holschuh linux-thinkpad@linux-thinkpad.org
Tue, 31 Dec 2013 11:42:26 -0200

On Tue, 31 Dec 2013, Henrique de Moraes Holschuh wrote:
> On Mon, 30 Dec 2013, Chris Schumann wrote:
> > >I am reading this, but I can't do much without access to a X1.  The
> > >thinklight control uses a specific ACPI method, so your X1 has it or it
> > >would not have turned anything off.
> Meh.  The "off" command uses the generic "update-cmos" handler (UCMS), which
> often just stores info in come nvram instead of doing something.  In the
> keyboard backlight case, the OFF command for the lights (thinklight and
> apparently backlight) actually turns them off, but if there is an ON
> command, it is command 0x0e (which is supposed to just toggle the
> thinklight).
> Please test it, see if thinkpad-acpi will give you the /proc/acpi/ibm/cmos
> file.  If it still does in your kernel, echo "0x0e" > /proc/acpi/ibm/cmos
> might be useful.  Other interesting cmos commands might be 0x0b to 0x0d.

It is also available in sysfs (far more likely to be supported than the
/proc node in a recent kernel).  It is likely at

  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh