Lenovo ThinkPad T520

Hardware	PCI/USB ID	Working?
Bluetooth	`0a5c:217f`	Yes
Webcam	`04f2:b217`	Yes
Ethernet	`8086:1502`	Yes
WLAN (Intel)	`8086:0084`	Yes
	`8086:0085`	Yes
	`8086:4238`	Yes
WLAN (Realtek)	`10ec:8176`	Yes
WWAN	`0bdb:1911`	Untested
GPU (Intel)	`8086:0116`	Yes
GPU (Intel)	`8086:0126`	Yes
GPU (NVIDIA)	`10de:1057`	Yes
Touchpad		Yes
Trackpoint		Yes
Keyboard		Yes
Fingerprint reader	`147e:2016`	Untested
Smart card reader	`17ef:1003`	Untested
SD card reader	`1180:e822`	Untested
SD card reader	`1180:e823`	Yes
Audio	`8086:1c20`	Yes

The larger 15-inch variant of the Lenovo ThinkPad T420.

Accessibility

The appearance of the ThinkPad Setup program (i.e., the tool used to configure UEFI BIOS settings) is simple and uses contrasting colours, so it may work well with OCR software. A legend of keyboard navigation shortcuts is also clearly listed on the bottom of the screen.

Note: Blind users should request the help of a sighted person to change UEFI BIOS settings. Keyboard beeps in the ThinkPad Setup program are enabled by default but only happen when unmanageable/invalid key combinations are pressed.

The user guide has a section under Chapter 8, "Advanced configuration", titled "ThinkPad Setup" that highlights the steps need to configure the UEFI BIOS settings. Relevant keyboard shortcuts (including those needed to trigger certain features on device startup) are also mentioned throughout:

Key	Effect
`ThinkVantage`	Interrupt normal startup and bring up the Startup menu
`F1`	Start the ThinkPad Setup program
`F12`	Bring up the Boot Menu window

Firmware

fwupd does not support this device yet.

Graphics

Selecting the graphics device

(This section only applies if your laptop also comes with the NVIDIA graphics card.)

Selecting a graphics device can be done by entering the ThinkPad Setup program and selecting one of the following options from Config > Display > Graphics Device:

Integrated Graphics
Discrete Graphics
NVIDIA Graphics

See Intel graphics, NVIDIA, and NVIDIA Optimus or Bumblebee for more details.

Note:

The DisplayPort will not work in Integrated Graphics mode since it is hardwired to the NVIDIA graphics card. One of the other modes must be used to make the DisplayPort available.
A maximum of one external monitor can be used in Discrete Graphics mode since the NVIDIA (discrete) graphics card can only drive two screens at most (including the laptop's built-in screen). NVIDIA Optimus can be selected instead for configurations with more than one external monitor.
OS Detection for NVIDIA Optimus must also be set to Disabled if you want to use NVIDIA Optimus.

Screen freeze in Discrete Graphics mode

In Discrete Graphics mode, GRUB's framebuffer can freeze the screen before the login prompt appears. Disabling the framebuffer resolves this issue.

Touchpad

libinput does not support horizontal edge scrolling on the T520's touchpad.

Function keys

Key	Visible?¹	Marked?²	Effect
`Fn`	Yes	No	`XF86Wakeup`
`Fn+F2`	Yes	Yes	`XF86ScreenSaver`
`Fn+F3`	Yes	Yes	`XF86Battery`
`Fn+F4`	Yes	Yes	`XF86Sleep`
`Fn+F5`	Yes	Yes	`XF86WLAN`
`Fn+F6`	Yes	Yes	`XF86WebCam`
`Fn+F7`	Yes	Yes	`XF86Display`
`Fn+F8`	Yes	Yes	`XF86TouchpadToggle`
`Fn+F9`	Yes		`NoSymbol`
`Fn+F12`	Yes	Yes	`XF86Suspend`
`Fn+PageUp`	No	Yes	Toggles the ThinkLight
`Fn+Home`	Yes	Yes	`XF86MonBrightnessUp`
`Fn+End`	Yes	Yes	`XF86MonBrightnessDown`
`Fn+Space`	No	Yes	None
`Fn+PrintScreen`	Yes	Yes	`Alt_L` `Alt_L+Sys_Req`
`Fn+ScrollLock`	Yes	Yes	`Num_Lock`
`Fn+Pause`	Yes	Yes	`Control_L+Break`
`Fn+Down`	Yes	Yes	`XF86AudioPlay`
`Fn+Up`	Yes	Yes	`XF86AudioStop`
`Fn+Right`	Yes	Yes	`XF86AudioNext`
`Fn+Left`	Yes	Yes	`XF86AudioPrev`

The key is visible to xev and similar tools.
The physical key has a symbol on it, which describes its function.

Note: Pressing Fn+ScrollLock even once (to toggle Num Lock) will cause subsequent Fn+ScrollLock key presses to become invisible to xev and similar tools until the system is rebooted.

Tip: Fn key lock can be enabled in the BIOS settings. When this option is enabled, pressing Fn once keeps the key in a pressed condition, similar to sticky keys. Pressing Fn twice will keep it in a locked stated until Fn is pressed again.