Lenovo Tab 4 8 (lenovo-tb8504f)

Features
Flashing	Works
USB Networking	Works
Internal storage
SD card
Battery	Works
Screen	Works
Touchscreen	Partial
Multimedia
3D Acceleration	Broken
Audio
Camera
Camera Flash
Connectivity
WiFi	Broken
Bluetooth	Partial
GPS
NFC
Miscellaneous
FDE
USB OTG	Works
HDMI/DP
Sensors
Accelerometer
Ambient Light
Proximity
Haptics
Barometer

Lenovo Tab 4 8
	; A Lenovo Tab 4 8 running postmarketOS
Manufacturer	Lenovo
Name	Tab 4 8
Codename	lenovo-tb8504f
Released	2017
Type	tablet
Hardware
Chipset	Qualcomm APQ8017
CPU	1.4 GHz Cortex-A53
GPU	Adreno 306
Display	800x1280 IPS LCD
Storage	16GB
Memory	2GB
Architecture	aarch64
Software
Original software	Android
Original version	7.0
postmarketOS
Category	testing
Pre-built images	no
postmarketOS kernel	3.18.140
Unixbench Whet/Dhry score	1166.2

This page is about WiFi-only tablet lenovo-tb8504f. For LTE tablet, see lenovo-tb8504x.

Contributors

Angus-g

Users owning this device

Unlocking

In developer options the allow oem unlock toggle may be unexpectedly disabled. In this case, try a software update to confirm latest (final) version, similar to tb-8504f_s001019_190909_row. The fastboot key combo is volume down + power. No device-specific information (e.g., bootloader version) is presented on the fastboot splash screen. fastboot getvar all shows some basic details. The standard unlock command fastboot oem unlock gives a warning and shows the correct command.

Installation

Install TWRP (3.2.3 and 3.3.1 are available). Format the System partition to prepare for the postmarketOS image. Either install from a recovery zip directly in TWRP, or use pmbootstrap flasher as usual.

Note: install from a recovery zip using sdcard or via sideload fail with the initramfs-extra not found splash screen.

Status

Using the LineageOS kernel (which is derived from Lenovo's open-sourced kernel), we can boot to a graphical display with USB networking. If CONFIG_USB_G_ANDROID is not set, it seems that there are a lot of errors regarding charging when connected via USB, and the boot doesn't get through to init. The touchscreen is detected, but the driver gets disabled in libinput due to a kernel bug.

Hardware details

Chipset

The chipset appears to be APQ8017, with an Adreno 300-series GPU. It seems to be very similar (at the devicetree level) to MSM8917. Neither of these currently have a mainline kernel effort. Wikipedia suggests the Snapdragon 425 MSM8917 is software-compatible with MSM8937.

The values are estimated strictly from software, not hardware, results (fastboot, adb, or twrp-3.3.1-1-TB8504 [unified 8504f/x)], using the commands given below.

chipset details (software-derived)

feature	value	source
variant	QRD eMMC	fastboot
product	QC_REFERENCE_PHONE	fastboot
baseband		fastboot
bootloader		fastboot
kernel	3.18.71-perf-gec07f0ae-dirty Aug 2019	adb
Hardware	Qualcomm Technologies, Inc APQ8017	adb
CPU max freq (KHz?)	1401000	twrp
CPU min freq (KHz?)	960000	twrp
GPU model	Adreno306v33	twrp
GPU max freq (Hz)	598000000	twrp
GPU min freq (Hz)	270000000	twrp
GPU target freq (Hz)	400000000	twrp
compatible	qcom,msm8917-qrd-sku5	twrp
model	Qualcomm Technologies, Inc. MSM8917-PMI8937 QRD SKU5	twrp
Bluetooth	?	(8017 is 4.2, 8917 is 4.1?)

sample commands (software-derived)

 fastboot getvar all
 cat /proc/version
 cat /proc/cpuinfo
 cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
 cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq
 cat /sys/class/kgsl/kgsl-3d0/gpu_model
 cat /sys/class/kgsl/kgsl-3d0/max_clock_mhz
 cat /sys/class/kgsl/kgsl-3d0/max_gpuclk
 cat /sys/class/kgsl/kgsl-3d0/min_clock_mhz
 cat /sys/class/kgsl/kgsl-3d0/devfreq/target_freq
 cat /sys/firmware/devicetree/base/compatible
 cat /sys/firmware/devicetree/base/model

CPU Tuning

According to cpufreq-info (cpufrequtils package), the chipset does indeed have a tiny frequency range, 960MHz - 1.4GHz. Benchmarks (ubench) show trivial differences in performance between the available frequency governors (default is performance), and all result in thermal throttling (frequency limiting).

Battery

Charging works, monitor via systool -v -c power_supply

Sensors

Output of sudo hwtest

hwtest output

Category	Model	Path	Status	Value
framebuffer	mdssfb_80000	/sys/class/graphics/fb0	Working	U:800x1280p-60
framebuffer	mdssfb_a0000	/sys/class/graphics/fb1	Working
input	gpio-keys	/dev/input/event3	Working
input	hbtp_vm	/dev/input/event2	Working
input	fts_ts	/dev/input/event1	Working
input	qpnp_pon	/dev/input/event0	Working

hwtest output (kleintux 20221119)

Category	Model	Path	Status	Value
framebuffer	mdssfb_80000	/sys/class/graphics/fb0	Working	U:800x1280p-60
framebuffer	mdssfb_a0000	/sys/class/graphics/fb1	Working
input	himax-touchscreen	/dev/input/event3	Working
input	gpio-keys	/dev/input/event2	Working
input	hbtp_vm	/dev/input/event1	Working
input	qpnp_pon	/dev/input/event0	Working

Output of sensors (lm-sensors package):

sensors output

$ sensors
battery-virtual-0
Adapter: Virtual device
temp1:        +26.0C  

xo_therm-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

xo_therm_buf-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

case_therm-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor0-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor1-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor2-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor3-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor4-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor5-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor6-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor7-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor8-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

tsens_tz_sensor9-virtual-0
Adapter: Virtual device
temp1:         +0.0C  

pm8937_tz-virtual-0
Adapter: Virtual device
temp1:        +28.7C  (crit = +145.0C)

pa_therm0-virtual-0
Adapter: Virtual device
temp1:         -0.0C

For reference, output of sensorssandbox (v1.8, f-droid):

sensorssandbox results

sensor	vendor
BMA255 Accelerometer / Temperature / Double Tap	Bosch
Step Detector	QTI
Step Counter	QTI
Significant Motion Detector	QTI
Tilt Detector	QTI
Basic Gestures	?
Facing	?
Pedometer	QTI
Motion Accel	QTI
Coarse Motion Classifier	?

Photos

|