Trekstore Surftab Wintron 7.0 III: Linux

See post about hardware: https://technikgebastel.blogspot.de/2016/03/trekstore-surftab-wintron-70-i-hardware.html
See post about UEFI: https://technikgebastel.blogspot.de/2016/03/trekstore-surftab-wintron-70-i-uefi.html
See post about Linux: https://technikgebastel.blogspot.de/2016/04/trekstore-surftab-wintron-70-iii-linux.html

Current status:

What works (tested):
- booting Debian or Ubuntu with XFCE4, i3, Gnome3
- display: brightness change, screen rotation, video playback
- touchscreen (GSL1686): calibration, multitouch input (including multitouch gestures in Gnome3)
- Wireless (rtl8723bs)
- USB-OTG
- micro-SD card slot
- battery charge state (AXP288)

- orientation sensor (bma22e with BMA2x2)

What probably works (not tested):
- Bluetooth (rtl8723bs)

What does not yet work:
- audio output (ALC5651 not supported with linux kernel 4.3, included starting 4.5, but wlan-patches for 4.5 cause problems)
- cameras (gc0310, ov2680)

What will probably never work, aka no idea how to make it work:
- hardware buttons (except power button)

Once everything except stuff in the category "What will probably never work, aka no idea how to make it work:" is working, I will document everything here.

Trekstore Surftab Wintron 7.0 II: UEFI

See post about hardware: https://technikgebastel.blogspot.de/2016/03/trekstore-surftab-wintron-70-i-hardware.html
See post about UEFI: https://technikgebastel.blogspot.de/2016/03/trekstore-surftab-wintron-70-i-uefi.html
See post about Linux: https://technikgebastel.blogspot.de/2016/04/trekstore-surftab-wintron-70-iii-linux.html

The nice thing about the Trekstore Surftab Wintron 7 is that is has a proper UEFI, because it is delivered with Windows 10.

When attaching a keyboard via microUSB and pressing ESC while booting, we first see a general screen, where we can choose several things to do:

 Boot Manager: Choosing "Boot Manager", we find all startup entries that are registered in the UEFI.

 Device Management:

Boot from File:

Secure Boot Option:  Although not activated when shipped, it seems to be possible to deactivate it. Furthermore all the functionality to load own keys seems to be there.

SCU (System control unit of the Intel SOC): I was completely astonished by the functionality and options included here.

We can even get an old-school boot output!!!

Trekstore Surftab Wintron 7.0 I: Hardware

See post about hardware: https://technikgebastel.blogspot.de/2016/03/trekstore-surftab-wintron-70-i-hardware.html
See post about UEFI: https://technikgebastel.blogspot.de/2016/03/trekstore-surftab-wintron-70-i-uefi.html
See post about Linux: https://technikgebastel.blogspot.de/2016/04/trekstore-surftab-wintron-70-iii-linux.html

Recently a colleague of mine made me aware of a very cheap 7 inch Windows 10 tablet. Even though he intended to use it with Windows 10, when searching for the specs I came across some forum posts of people that tried to run Ubuntu instead of Windows on it.
The Trekstore Surftab Wintron 7 (http://www.trekstor.de/detail-surftabs-de/product/produktsupport/product/surftab-wintron-70-v2.html) costs about 50 Euro.
Motivated by Ron and Frank Riegers talk about the 32C3 (https://www.youtube.com/watch?v=DBv0eykj_m8&feature=youtu.be&t=1h5m35s) I started to tackle the problem of getting Debian to run on this device.

The inside looks like:

Specifications:
Display: 7 inch, 1024x600, IPS
CPU: Intel Atom Z3735G (http://ark.intel.com/de/products/80275/Intel-Atom-Processor-Z3735G-2M-Cache-up-to-1_83-GHz)

PMIC: AXP288 (http://www.x-powers.com/product/AXP288_en.php)

RAM: 1 GB DDR3, Kingston N11915-01, D2516EC4BXGGB (http://media.kingston.com/pdfs/emmc/MKF_585_DDR3_3L_US.pdf)

CMOS Flash memory: 64 Mbit 25LQ64GVIG

internal memory: 16 GB, FORESEE NCEMBS99-16GB

cameras: front 0.3 MP, back 2 MP

Audio: ALC5651, internal speaker (mono), 3,5mm external connector

Wireless/Bluetooth: RTL8723BS, 802.11 b/g/n, 2.4 GHz

Touchscreen: 5 fingers, Silead GSL1686

battery: 2500 mAh, 3.7V

microSD: SDHC, SDXC

microUSB: host and client mode

orientation sensor BMA222E (BMA2x2)

cameras: Gcoreinc gc0310, OmniVision 2680