You are not logged in.
Pages: 1
I have arch working reasonably well on a 2016 12" Macbook. I can't work out out to turn on the keyboard backlight. On other mac laptops I've used "/sys/class/leds/smc::kbd_backlight" to set the backlight brightness, but that directory isn't present. I have the kernel module "applesmc" loaded (is that module responsible for the leds?).
Possibly related, I have a capslock led directory. Pressing the capslock key toggles the value in "brightness" between 0 and 1, but the capslock led never turns on, even when I write a 1 to the file.
$ ls /sys/class/leds/input6::capslock
power/ brightness device max_brightness subsystem trigger uevent
Also possibly related, unlike most mac laptops, the keyboard (and trackpad) aren't connected by internal usb, but by spi. I'm using this driver with a kernel I compiled myself.
Any ideas what the problem might be?
Offline
More information:
$ dmesg | grep applesmc:
[ 4.419517] applesmc: key=685 fan=0 temp=37 index=36 acc=0 lux=2 kbd=0
Looking at the code in the applesmc module that prints that, it looks like it's not detecting the backlight:
pr_info("key=%d fan=%d temp=%d index=%d acc=%d lux=%d kbd=%d\n",
s->key_count, s->fan_count, s->temp_count, s->index_count,
s->has_accelerometer,
s->num_light_sensors,
s->has_key_backlight);
The module seems to determine the presence of features by querying a key value store. The key corresponding to the keyboard backlight is:
#define BACKLIGHT_KEY› › "LKSB" /* w-o {lkb (2 bytes) */
Is anyone familiar with how the key value store is populated? Could it be that on this laptop a different key is used for the backlight?
Offline
Assuming the backlight is controlled by the SMC, it looks like the 12" macbook uses a different name for the SMC entry (other than "LKSB"). It looks like the SMC key names are not public, or at least I can't find them. I found a tool for dumping the contents of an SMC entry for a given key: https://github.com/jballard1991/softwar … cDumpKey.c, but there's no way to list all valid keys short of brute forcing all of them, and even if I had a list of all valid keys, I don't know how I'd work out which one corresponds to the backlight. Some of the SMC entries relate to power management, so I don't really want to try writing to random entries until one works in case I break something.
Does anyone know if the keyboard backlight is controlled by the SMC, and if so, how one might go about finding the corresponding key?
Offline
Also possibly related, unlike most mac laptops, the keyboard (and trackpad) aren't connected by internal usb, but by spi. I'm using this driver with a kernel I compiled myself.
Would it be possible for you to explain how you did this? I have arch running relatively well, the only things left to figure out are the problems pertaining to the keyboard. Any help or direction is very, very appreciated.
Thanks.
Offline
Are you talking about a macbook 12 early 2016, model 9,1 ?? because i had to use the aur spi driver to get keyboard to work at all, but once that driver was installed the keyboard backlight worked fine. I am seeking a fix on sound and bluetooth. Are sound and bt working on your unit and is your unit an early 2016 9,1 machine ?
using current kernel 4.12 i still had to use kernel option 'intremap=nosid' to get it to boot. but the keyboard backlight works fine.
Offline
Pages: 1