[ltp] Thinkpad Tablet 10 1st gen Linux working - mostly

[Nicole Færber]

Hi,

for those interested in alternate operating systems for your Thinkpad
Tablet 10 1st generation (CPU Z3795) I have good news - Linux is to some
extent working pretty well!

I am tinkering with it for quite some time now and wrote about it, on my
homepage:

https://www.dpin.de/nf/computer-it-nerdine-geek/geraete-devices-toys/thinkpad-tablet-10/

and in my blog:

https://www.dpin.de/nf/category/geek-stuff/devices/

If you like to stay in touch or even better if you want to join the
effort, you might want to subscribe to the mailinglist I created for it:

http://dpin.de/cgi-bin/mailman/listinfo/tpt10-linux

BTW I am using CaCert SSl certificates, either trust them or add the
CaCert root certificate to your browser:

https://www.cacert.org/index.php?id=3

Current status:

- system boots fine, runtime is 99.8% stable

- internal eMMC working well (the old eMMC hangs are solved with more
recent kernels >= 4.6)

- GPU support is working (OpenGL hardware acceleration and video
decoding, fullHD playback 20-30% CPU)

- LCD backlight control working

- runtime power management is good, we are ~1-1.5W lower than Win10

- Wifi working well

- Bluetooth 4 working well

- most sensors working through IIO (ambient light, accel, gyro)

- lid switch working

- buttons working (vol +/-, rotation lock button, power button, windows
button (on glass))

- since two weeks audio is working too - jippie!

- There is a bug in the TPT10 ACPI DSDT table which advertises the audio
codec as a RT5640 but in fact it is RT5671,

- I am wondering how Win10 works around this?

- Sierra EM7345 4G modem working

- low power suspend-to-idle working - gives ~3.5 days standby time,
which is less than Win10, so we are missing some power saving tweaks here

- USB2 and USB3 (through dock) working

- external HDMI working

- docking station fully supported (sound, ethernet, USB3 ports, HDMI port)

- touchscreen, with full multitouch support

- digitizer (pen)


Not working or unstable:

- Cameras, these require Intel Image Signal Processor support plus
hardware adaptation.

- Especially the hardware adaptation is unlikely to happen without
support by Lenovo.

- Fingerprint reader Synaptics VFSI6101 - there is absolutely no
documentation available for this chip and the hardware manufacturer is
not willing to give it to me :(

- Broadcom GPS/GNSS BCM47521, interesting device since it outputs raw
satellite receive data and software needs to calculate the solution.
Attached to UART, I can talk to it but have no idea about the protocol
and there is no documentation available for it

- Broadcom NFC BCM2079x, another of these undocumented chips but at
least there are some driver snippets and Android NFC HAL code floating
around so this could probably be made to work even without docs, but it
means quite some effort

- Battery and AC status is not working out of the box. ACPI reports
battery and AC status using ACPI operation region methods but these do
not work since they are operating on I2C address 0x78 which is an
"unusual address" and the kernel reports I2C read errors. There is also
a battery controller on I2C 0x70 which I could get to report sane
values, code is here:
https://www.dpin.de/gitweb/?p=tpt10-bat.git;a=summary

- So we have a workaraound and mybe we'll find a way to get around the
0x78 issue as well.

- Baytrail only supports suspend to idle (in Linux called "freeze").
This mode is not super well supported and sometimes causes IRQ storms on
resume also causing (seldomly) a resumed device to unexpectedly freeze
or misbehave. There is also the issue that the standby power drain is
too high, we are obviously lacking some knowledge about the hardware to
better tune this.

The TPT10 is a very nice highly portable Linux machine. In connection
with the hardware keyboard it almost feels like a small laptop, really
cool! In connection with the dock and an USB3 harddisk plus big screen
it almost feels like a small workstation. This is what makes it so
attractive to me.


If someone from Lenvo is reading this: PLEASE help us to better support
the TPT10! Get in touch with me.

Have fun,
cheers
  nicole


PS: The 2nd generation TPT10 could be interesting too, Cheerytrail could
even have better Linux support but the device is still too expensive for
me to buy as another hacking target.

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