Re: [ibm-acpi-devel] [PATCH] thinkpad_acpi: Add support for keyboard backlight

[Kevin Locke]

On 01/12/2016 08:07 AM, Henrique de Moraes Holschuh wrote:
> On Mon, Jan 11, 2016, at 19:12, Johannes Stezenbach wrote:
> > I can confirm this, my x230 has both.  FWIW, BIOS hotkey
> > Fn+Space cycles through off, dim backlight, full backlight
> > and full thinklight. /sys/class/leds/tpacpi::thinklight/brightness
> > can be read (showing either 0 or 255) but writes are ignored.
> > Dito for /proc/acpi/ibm/light.
>
> We likely need to integrate better (future work) the new backlight
> control with the thinklight control and the firmware interface in the
> x230.
>
> Is the ACPI AML for fn+space readable enough, or is it trapping directly
> into SMM?  Because if it interacts with the traditional higher-level
> ACPI AML we already use to talk to the thinklight (and now to the
> backlight), it should be relatively easy to fix the driver to better
> support the x230.

I looked through the DSDT and SSDT AML on the T430 (which also has both 
a keyboard backlight and ThinkLight) and couldn't deduce which method 
was being invoked for Fn+Space or an analog to MLCG/MLCS for the 
ThinkLight.  However, that may be due to my inexperience interpreting 
AML.  I'll keep looking/learning.

I've posted the files online if anyone else has time/interest to take a 
look:  https://kevinlocke.name/misc/t430-acpi/

Best regards,
Kevin