[[!meta title="Status of Linux on the MacBook Air 4,2"]]

## Introduction

Following up my 
[[recent|macbook-air-42-correcting-multimedia-key-mapping-and-status]]
[[posts|macbook-air-42-touchpad-keyboard-correct-screen-resolution]]
[[about the MacBook Air 4,2|macbook-air-42-archlinux]] with Linux,
here's a status report of what works and what is still missing.

This report is based on ***Linux 3.2.0-rc5***.

## Screen Resolution and external screens

Great news, Linus' tree merged patches necessary for full screen resolution
and external screens work as well:

    Screen 0: minimum 320 x 200, current 2560 x 2340, maximum 8192 x 8192
    eDP1 connected 1440x900+0+1440 (normal left inverted right x axis y axis) 30mm x 179mm
       1440x900       60.0*+
    VGA1 disconnected (normal left inverted right x axis y axis)
    HDMI1 disconnected (normal left inverted right x axis y axis)
    DP1 disconnected 2560x1440+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
    HDMI2 disconnected (normal left inverted right x axis y axis)
    HDMI3 disconnected (normal left inverted right x axis y axis)
    DP2 disconnected (normal left inverted right x axis y axis)
    DP3 disconnected (normal left inverted right x axis y axis)
      2560x1440 (0xb2)  241.5MHz
            h: width  2560 start 2608 end 2640 total 2720 skew    0 clock   88.8KHz
            v: height 1440 start 1443 end 1448 total 1481           clock   60.0Hz

An external monitor was tested via Mini-DP-to-HDMI adapter and Mini-DP-to-DVI
adapter with resolutions from 1920x1080 (24" Samsung) up to 2560x1440 (27" Dell).


## Keyboard/Multimedia Keys (FN+F1..F12)

With the current kernel all multimedia keys match correctly.


## Keyboard/Backlight

Keyboard backlight can be controlled using 
[kbsd](http://git.schottelius.org/?p=kbsd;a=summary). This works fine,
but it could be improved to react on the light sensor.
The question simply is, how to map the light sensor values to keyboard
backlight settings. If you've got a good table or function to apply,
drop me a mail, so I can include it.


## Touchpad

The touchpad works almost completly, the only
problem left is that
the mouse pointer does not move when the mouse button is pressed.
This may be a configuration problem of the synaptics touchpad, but
I haven't found a fix for this.


## Screen backlight

The nice utility **xbacklight** still does not work,

    [11:14] brief:~% xbacklight 
    No outputs have backlight property

but dimming works manually via echo:

    [21:15] brief:~# echo 2200 > /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness  

And the display is not switched off when lid is closed. 
ACPI reports the lid event, though. Probably a related problem.


## WLAN / brcmsmac / Broadcom BCM43224

This used to be fixed in my own patched kernel, but since I've got
a new macbook air 4,2, it does suffers the 
[network process hang issue in the **brcmsmac** driver](https://lkml.org/lkml/2011/10/18/145)
again. Iterating over several different kernels did not yet fix this problem.

Though interestingly after 2 suspend and resume cycles it works, until the 4th of 5th
suspend cycle, at which all network processes hang again, if the connection to the
AP is lost.

## Current problem summary

 * Clicking and moving the mouse pointer does not work
 * xbacklight does not recognise backlight controls
 * Display is not switched off on lid close
 * Network processes hang when the connection to the AP is lost/cannot be established

[[!tag net unix]]