Lenovo ThinkPad T400

Hardware	PCI/USB ID	Working?
Bluetooth	`0a5c:2145`	Yes
Webcam	`17ef:1004`	Yes
Ethernet	`8086:10f5`	Yes
Ethernet	`8086:10bf`	Yes
WLAN (Intel)	`8086:4237`	Yes
WLAN (Intel)	`8086:4236`	Yes
WLAN (Realtek)	`10ec:8172`	Yes
WWAN (Sierra)	`1199:0220`	Untested
WWAN (Ericsson)	`0bdb:1900`	Untested
GPU (Intel)	`8086:2a42`	Yes
GPU (ATI)	`1002:95c4`	Yes
Touchpad		Yes
Trackpoint		Yes
Keyboard		Yes
TPM		Untested
Fingerprint reader (STMicroelectronics)	`0483:2016`	Yes
Fingerprint reader (AuthenTec)	`08ff:2810`	Yes
CardBus slot	`1180:0476`	Untested
Smart card reader	`17ef:1003`	Untested
SD card reader	`1180:0822`	Yes
Memory Stick reader	`1180:0592`	Yes
xD card reader	`1180:0852`	No
Audio	`8086:293e`	Yes

Accessibility

The appearance of the BIOS Setup Utility is simple and uses contrasting colours, so it may work well with OCR software. A legend of keyboard navigation shortcuts is also clearly listed at the bottom of the screen.

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

Keyboard shortcuts needed to trigger certain features on device startup are mentioned throughout the hardware maintenance manual:

Key	Effect
`ThinkVantage`	Interrupt normal startup and bring up the Startup menu
`F1`	Start the BIOS Setup Utility
`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 ATI graphics card.)

Both the Intel graphics card and the optional ATI graphics card must be turned on to allow graphics switching by restarting Xorg. Selecting a graphics device can also be done by entering the BIOS Setup Utility and selecting one of the following options from Config > Display > Graphics Device:

Integrated Graphics
Discrete Graphics
Switchable Graphics

See Intel graphics, ATI, and Hybrid graphics for more details.

Hardware video acceleration

Intel graphics#Hardware accelerated H.264 decoding on GMA 4500 suggests installing libva-intel-driver-g45-h264^AUR instead of libva-intel-driver to enable support for hardware accelerated H.264 video decoding on the Intel graphics card.

The output of vainfo will indicate that H.264 decoding (with libva-intel-driver-g45-h264 installed) is supported by the VA-API driver, but this is misleading. Attempting to play an H.264 encoded video with mpv and hardware acceleration results in the screen momentarily freezing. This may ultimately lead to a session reset which will force you back to the login screen. Session resetting seems to happen more frequently with the modesetting driver compared to the xf86-video-intel driver.

Visually corrupted GRUB menu

GRUB's framebuffer may cause the GRUB menu to disappear or appear "corrupted" during the boot process. Fortunately, the menu will still be functional even without visual aid. This issue can be resolved by disabling GRUB's framebuffer.

Touchpad

Although libinput is recommended over Touchpad Synaptics, the latter driver provides more touchpad scrolling options, namely:

Horizontal and vertical edge scrolling.
Horizontal and vertical two-finger scrolling.
Circular scrolling.

libinput, on the other hand, only supports vertical edge scrolling for this particular touchpad.

Touchpad Synaptics

Note that two-finger pressure may need to be decreased in order to increase the responsiveness/sensitivity of two-finger scrolling. This can be done by decreasing the default value of 282 to a value like 50:

$ xinput set-prop 'SynPS/2 Synaptics TouchPad' 'Synaptics Two-Finger Pressure' 50

You can experiment with different values to find something that works for you. See synaptics(4) for more input device properties (and configuration options), e.g., selecting the scrolling method. See Touchpad Synaptics#Configuration for making the above change persistent across sessions.

Mute key

T400 laptops with BIOS versions older than 3.01 (7UET71WW) may need to pass acpi_osi=Linux as a kernel parameter to allow the mute key to function as intended. See https://thinkwiki.org/wiki/Mute_button and the relevant thread on the linux-acpi mailing list for more details.

Power management

Fan speed control

See Fan speed control#ThinkPad laptops.

Function keys

Key	Visible?¹	Marked?²	Effect
`Fn`	Yes	Yes	`XF86WakeUp`
`Fn+F1`	No		Reserved³
`Fn+F2`	Yes	Yes	`XF86ScreenSaver`
`Fn+F3`	Yes	Yes	`XF86Battery`
`Fn+F4`	Yes	Yes	`XF86Sleep`
`Fn+F5`	Yes	Yes	`XF86WLAN`
`Fn+F6`	Yes	No	`XF86WebCam`, reserved³
`Fn+F7`	Yes	Yes	`XF86Display`
`Fn+F8`	Yes	Yes	`XF86TouchpadToggle`
`Fn+F9`	Yes	Yes	`NoSymbol`
`Fn+F10`	Yes	No	`XF86WakeUp`, reserved³
`Fn+F11`	No		Reserved³
`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+PrtScr`	Yes	Yes	`Alt_L` `Alt_L+Sys_Req`
`Fn+ScrollLock`	Yes	Yes	`Num_Lock`
`Fn+Pause`	Yes	Yes	`Control_L+Break`

The key is visible to xev and similar tools.
The physical key has a symbol on it, which describes its function.
The key is marked as "reserved" in the hardware maintenance manual.

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. However, the Num Lock LED indicator will still function and correctly indicate whether Num Lock is enabled.

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.