Luke Ross

Linx 820

3 commits linx820-master-2018-05-01.tar.gz git clone https://lukeross.name/projects/linx820.git/

Notes on running Linux on a Linx 820 tablet.

master /

README.md Update 4 months ago

README.md

# linx-820

Notes on running Linux on a Linx 820 tablet; I'm using Ubuntu Artful.

## BIOS

Hold down Volume-Up whilst turning on. From here you can turn off secure boot
(you need a keyboard plugged in, F8? I think to save changes).

## Installing Ubunu

Write the image to an SD card. Enter BIOS and pick the SD card off the
boot menu. It'll stop at the Grub prompt; enter:

```
set root=(hd1)
configfile /boot/grub/grub.cfg
```

It'll then be fine. I suggest not removing the two recovery partitions;
just replace the Windows install.

## Display

Intel graphics (PCI). Mostly worked with no configuration including micro-HDMI
(but no sound).
However the backlight will not come on and/or Xorg will crash unless you
put these into /etc/initramfs.conf/modules:

```
overlay
pwm-lpss
pwm-lpss-platform
```

After doing this, run `update-initramfs -u`.
https://linuxiumcomau.blogspot.co.uk/2017/05/gui-isorespinsh.html
will take care of this for you.

*Warning*: Upgrades to initramfs tend to wipe this file, causing gdm to not
start on the next reboot. This can include any updates installed during
the installation process!

## Touchscreen

Goodix Capacitive TouchScreen (i2c). Needed no configuration

## Wifi

Intel Corporation Wireless 3165 (PCI). Needed no configuration

## Bluetooth

Intel Bluetooth (USB). Needed no configuration

## Speakers

LPE + RT5651. Haven't got these working yet; see headphone section.

## Headphone socket

The HDMI sound driver currently causes PulseAudio to crash; disable it
by adding an entry into modprobe.conf:

```
blacklist snd_hdmi_lpe_audio
```

I also need the UCM information for the `bytcr-rt5651` from
https://github.com/plbossart/UCM

From kernel 4.17 jack-detect works properly.

## HDMI audio

Not yet working.

## Accelerometer

MIRAMEMS da280 (i2c). da280 driver works from kernel 4.16 or use
the patch from
https://www.spinics.net/lists/linux-iio/msg36010.html

Also needed a udev hardware DB entry (or else the vertical
display is flipped):

```
sensor:modalias:acpi:MIRAACC*:*
 ACCEL_MOUNT_MATRIX=1, 0, 0; 0, -1, 0; 0, 0, 1
```

## USB (both as host and device)

PCI.  It's `xhci` for the host most and `dwc3-pci` as a gadget.

In general, it'll work in whatever mode you boot it in, and won't change
afterwards (affecting charging). There's some support in 4.17 for
mode change - I can seem to change from host to device, but not the
other way.

## Camera

2 x OV2680 (i2c via ISP). Driver's in staging at
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/staging/media/atomisp

## Charging LED

Not yet known. I2C?

## TPM

Not tested

## Suspend

Surprisingly, seems to work fine. However the power button on wake-up tends to immediately sleep
the device again. I set the power button to not sleep to avoid this.