[ltp] tpacpi bug in tpacpi::thinklight/brightness for X1 Carbon
Henrique de Moraes Holschuh
Mon, 30 Dec 2013 00:15:42 -0200
On Sun, 29 Dec 2013, Sandro wrote:
> The Lenovo X1 Carbon is gaining populairty as it's easily one of the
> prettiest alternatives to the McBook Air.
> For a while, I thought the keyboard backlight couldn't be controlled
> through tpacpi, period. After asking a question <
> http://askubuntu.com/questions/383501/> I got an interesting answer:
> The keyboard backlight can in fact be turned off using the following
> echo 0 > /sys/class/leds/tpacpi\:\:thinklight/brightness
> It's just that it cannot be turned /on/, which is what I am trying to do.
> I can't be certain, but if the current tpacpi can turn the light off, it
> gives me the impression that turning it on is just a bugfix away.
> I cannot find an issuetracker for Github or Sourceforce, so I thought maybe
> one of the devs (is that still Henrique de Moraes Holschuh AKA Hmh?) will
> read this.
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.
It likely wants a different parameter to enable the keyboard backlight
(which stands to reason, since it is not a thinklight). Since the turn-off
command worked, if we're lucky it is a bitfield and it can be used to
separately control the thinklight and the keyboard backlight.
I won't promise anything, but send me the ACPI dump of your X1 (update it to
the latest BIOS/EFI first). Use a recent version of the ACPI tools,
preferably "acpidump" from the latest Linux kernel tree (it is inside the
tools/power/acpi directory of the kernel source. Type Make there to build).
Your linux distro might have it packaged.
I also need the output of dmidecode. Remove all serial numbers and UUIDs
before you send it to me (replace their digits with "X").
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them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot