Linux kernel commit

The Bluetooth on my Acer laptop didn't work under Linux. At boot the kernel printed "Bluetooth: hci0: Opcode 0x0c03 failed: -110" and the interface stayed dead. Digging in, I found the chip was a MediaTek MT7921 inside a Lite-On module whose USB ID (04ca:3807) was missing from the btusb driver table: the driver loaded through a generic match, but without the BTUSB_MEDIATEK flag the firmware was never loaded.

The fix is two lines: add the ID to the table with the right flags. The genuinely interesting part was the process: preparing the patch the kernel way (checkpatch, properly formatted commit message), sending it by e-mail to the linux-bluetooth mailing list with git send-email, and following the review. The patch was accepted by maintainer Luiz Augusto von Dentz and merged into the mainline tree.

It's a tiny contribution at the scale of the kernel, but it fixes my own hardware, and that of everyone with the same laptop. That's exactly what I love about open source: hit a problem, understand it all the way down, and send the fix upstream instead of keeping it to yourself.