Xiaomi RedmiBook Pro 15 2022 Ryzen

Hardware	PCI/USB ID	Working?
Touchpad	`27C6:01E0`	Yes
Keyboard		Yes
GPU (AMD)	`1002:1681`	Yes
Wireless	`10ec:b852`	Yes
Bluetooth	`0cb8:c559`	Yes
Webcam	`2b7e:b557`	Yes
Audio	`1002:1640`	Yes
SD-card reader	`10ec:525a`	Yes
Fingerprint reader	`27c6:589a`	Untested

This laptop has two variants, one with dedicated NVIDIA graphics and one without.

Installation

See #Firmware.

Accessibility

The appearance of the UEFI is pretty simple and not very colorful, so it might work well with OCR software.

Note: Blind users should request the help of a sighted person to change UEFI settings

Firmware

This UEFI setup interface has very limited options available. You can disable/enable Secure Boot, set/unset password, change the size of shared VRAM, change boot order, or change the date/time. But that is about what all you can do in it. Pressing F12 during booting to select the boot device.

Note: This device does not have a BIOS speaker.

fwupd does not support this device yet.

Secure Boot

Enter the UEFI menu by pressing F2 during booting and disable the password and Secure Boot.

Security > Set password
Security > Disable Secure Boot
Reset the password by setting the password again but letting the New Password fields blank.

Microphone detection problem

This laptop has a SenaryTech SN6140 Audio chip. When an external microphone is plugged in the 3.5mm port, it may not be detected.

This only happens when the resistance of the microphone of the headset (with a 4-segment TRRS plug) is lower than usual. For example, the microphone of my Anker Soundcore Q35 headset has a resistance of about 1000Ω, while the microphone my other two headsets have a resistance of about 2000Ω. This is probably a bug in detecting whether an OMTP/CTIA headset is plugged in or just an headphone with no microphone is plugged in. Because the resistance of the speaker in the earcup is usually much lower than that of the microphone, the audio chip might be measuring the resistance to tell them apart, and mistakes a microphone with lower resistance as a speaker.

With that in mind, you may pick one from the following ways to solve or to workaround the problem. (Or just use another microphone)

Change the resistance

You can increase the resistance of the microphone to get it detected easily. You can add a resistor of a suitable value in series to the microphone, which requires some electronics work.

Reconfigure the audio chip with `hda-verb` command

With this method, you can plug in your headset in a normal way and no electronics work is required. However, I do not know what those commands actually do to the audio chip. Please only use them if you feel confident and adventurous.

Install the alsa-tools package.

Warning: All these commands come from a wild guess from https://github.com/torvalds/linux/blob/f7301f856d351f068f807d0a3d442b85b2c6a01d/sound/pci/hda/patch_conexant.c#L173 and my own experiment with no datasheet or documentation of SN6140 or any other similar chips available.

First, check and save the original value of the (potential) output current comparator threshold. Here /dev/snd/hwC1D0 is my device path. 0xb20 is the get-verb corresponding to the 0x320 set-verb. 0 is an unused parameter.

# hda-verb /dev/snd/hwC1D0 0x1c 0xb20 0
nid = 0x1c, verb = 0xb20, param = 0x0
value = 0x10

Here 0x10 is the unmodified value of the threshold register. Now, let's change it to some other value:

# hda-verb /dev/snd/hwC1D0 0x1c 0x320 0x08

This sets the threshold register to 0x08. This should lower the threshold by about 500Ω on my system. Your result may differ. Other useful values include 0x0, 0x18, 0x20 and 0x30. You may try different values. They seem to set different thresholds but I absolutely don't know why and how it works.

Your microphone should work with one of those values. This value seems to be persistent across reboots, and even useful when rebooting to a dual-boot Windows. After using the microphone, if you feel uncomfortable leaving that modified value, you can write back the original value:

# hda-verb /dev/snd/hwC1D0 0x1c 0x320 0x10

Substitute 0x10 to your save value if differ.

Plug in a two-step way

When you insert the plug of the headset, you can do it slowly and watch the audio input device list (for example in the KDE audio settings dialog). If you stop at a certain point, you may see a microphone appears in the list. Then you can resume the inserting and the microphone will keep working. This method has no potential harm of unknown commands, but requires unusual usage every time you plug in a microphone.

Fingerprint reader

The fingerprint reader requires a proprietary driver from an unknown third-party. The author explains that "The driver is developed with an internal async framework, which is not well-prepared to be open-sourced. So only the binary is released for the time being."