Difference between revisions of "ASUS C302"

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Revision as of 11:20, 16 September 2018

The Asus C302 (also known as Asus C302C and Asus C302CA) is a Chromebook, which can have Linux installed. Here are some pointers on the smooth running of Arch Linux.

Bootup

In /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi=Linux intel_iommu=on,igfx_off"

intel_iommu=on,igfx_off is from forum, to prevent the dmesg error:

[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

The CPU is an Intel Core M3, so install intel-ucode

Kernel Modules

In e.g. /etc/modprobe.d/skylake.conf

# Needed, for the nau8825 kernel sound modules to initialize
blacklist snd_hda_intel
options tpm_tis interrupts=0

Screen

The screen is 12.5 inches diagonally. At 1920x1080 resolution, this is 176 DPI.

In ~/.xinitrc:

xrandr --fbmm 277x156

Vsync

For proper vsync (including e.g. fullscreen Youtube in Firefox) in XFCE, install xfwm4-git (which also requires libxpresent), and enable XFCE's compositor.

Proper vsync also requires xf86-video-intel, rather than modesetting.

In /etc/X11/xorg.conf.d/20-intel.conf

Section "Device"
    Identifier "Intel Graphics"
    Driver "intel"
EndSection

Keyboard

To use the top row of Chromebook keys as useful keys in xorg, use e.g.:

In ~/.Xmodmap

keycode   9 = Escape NoSymbol Escape
keycode  22 = BackSpace BackSpace BackSpace BackSpace Delete NoSymbol Delete
keycode  37 = Control_L NoSymbol Control_L
keycode  50 = Shift_L NoSymbol Shift_L
keycode  66 = Caps_Lock NoSymbol Caps_Lock
keycode  67 = Home F1 Home F1 F1 F1 XF86Switch_VT_1
keycode  68 = End F2 End F2 F2 F2 XF86Switch_VT_2
keycode  69 = Prior F3 Prior F3 F3 F3 XF86Switch_VT_3
keycode  70 = Next F4 Next F4 F4 F4 XF86Switch_VT_4
keycode  71 = Delete F5 Delete F5 F5 F5 XF86Switch_VT_5
keycode  72 = XF86MonBrightnessDown F6 XF86MonBrightnessDown F6 F6 F6 XF86Switch_VT_6
keycode  73 = XF86MonBrightnessUp F7 XF86MonBrightnessUp F7 F7 F7 XF86Switch_VT_7
keycode  74 = XF86AudioMute F8 XF86AudioMute F8 F8 F8 XF86Switch_VT_8
keycode  75 = XF86AudioLowerVolume F9 XF86AudioLowerVolume F9 F9 F9 XF86Switch_VT_9
keycode  76 = XF86AudioRaiseVolume F10 XF86AudioRaiseVolume F10 F10 F10 XF86Switch_VT_10
keycode 111 = Up Up Up Up Prior Prior
keycode 112 = Prior NoSymbol Prior
keycode 113 = Left Left Left Left Home Home
keycode 114 = Right Right Right Right End End
keycode 115 = End NoSymbol End
keycode 116 = Down Down Down Down Next Next
keycode 117 = Next NoSymbol Next
keycode 118 = Insert NoSymbol Insert
keycode 119 = Delete NoSymbol Delete
keycode 121 = XF86AudioMute NoSymbol XF86AudioMute
keycode 122 = XF86AudioLowerVolume NoSymbol XF86AudioLowerVolume
keycode 123 = XF86AudioRaiseVolume NoSymbol XF86AudioRaiseVolume
keycode 124 = XF86PowerOff NoSymbol XF86PowerOff
keycode 167 = XF86Forward NoSymbol XF86Forward
keycode 182 = XF86Close NoSymbol XF86Close

(This list can be pruned.)

And then call it in ~/.xinitrc:

xmodmap ~/.Xmodmap

Touchpad

See TrackPoint - the pressure sensitivity can be changed:

In /etc/udev/hwdb.d/99-touchpad-pressure.hwdb

libinput:name:*Elan Touchpad:dmi:*svnGOOGLE:*pnCave*
 LIBINPUT_ATTR_PRESSURE_RANGE=1:41

Current libinput bug report.

Mouse

Due to the limited amount of USB ports, a Bluetooth mouse is a good option. The Logitech M590 mouse works great.

Run "bluetoothctl power on &" at startup, e.g. in ~/.xinitrc

In e.g. /etc/X11/xorg.conf.d/99-mouse.conf

Section "InputClass"
    Identifier "Logitech M590"
    MatchIsPointer "on"
    MatchDevicePath "/dev/input/event*"
    Driver "libinput"
    Option "AccelProfile" "flat"
EndSection

Then, the "speed" of the mouse can be set using the XFCE GUI, in "Settings - Mouse", setting the "acceleration" to e.g. 2.0

Sound

Sound is a work in-progress. Sound is reliable when using headphones only.

Save the audio firmware as /lib/firmware/9d70-CORE-COREBOOT-0-tplg.bin (filesize 23120 bytes).

To set audio to a sensible level, run in ~/.xinitrc:

amixer -q -c0 sset Headphone 70% &

Pulseaudio

To prevent audio "clicks", comment out "load-module module-suspend-on-idle" in /etc/pulse/default.pa and /etc/pulse/system.pa

Coil Whine

There is occasional coil whine, with no apparent method to reduce/eliminate it.