Introduction

I'm using Magic Trackpad 2 on Ubuntu 20.04 LTS Sometimes the cursor freezes, as shown below.

Comfortable use of Magic Trackpad 2 on Ubuntu desktop

When the battery capacity of Magic Trackpad 2 is decreasing, Because it was operating to disconnect the connection to reduce battery consumption, The cursor was stuck, wasn't it?

So, like this person's response, targeting only Magic Trackpad 2 I will apply a patch to the kernel that turns off the function that reduces battery consumption.

1. Prepare a Docker container for Ubuntu Kernel build

This will be helpful.

Ubuntu Weekly Recipe --Let's build the 333rd kernel package

I don't like the environment for building the Ubuntu kernel when the desktop environment gets dirty. I will build it on Docker.

docker pull ubuntu:focal
docker run -it --name ubuntu ubuntu:focal bash

On the Docker container, install the packages required for kernel build.

apt update && apt upgrade -y
apt install -y git fakeroot build-essential libncurses5 libncurses5-dev libelf-dev binutils-dev devscripts u-boot-tools
sed 's/# deb-src/deb-src/g' -i /etc/apt/sources.list
apt update
apt-get -y build-dep linux

2. Patch the Ubuntu Kernel

Download the kernel source.

cd
git clone git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal
cd focal

Since the kernel version of Ubuntu desktop is below

uname -a
Linux ryzen 5.4.0-42-generic #46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Check out the kernel source for the same version.

git tag -l Ubuntu-5.4.0-42*

Ubuntu-5.4.0-42.46

git checkout -b focal+mt2patch Ubuntu-5.4.0-42.46

Apply the patch.

apt install -y vim
vim drivers/hid/hid-input.c

git diff

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index dea9cc65bf80..194231ffabee 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -310,6 +310,9 @@ static const struct hid_device_id hid_battery_quirks[] = {
        { HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
                USB_DEVICE_ID_APPLE_ALU_WIRELESS_ANSI),
          HID_BATTERY_QUIRK_PERCENT | HID_BATTERY_QUIRK_FEATURE },
+       { HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE,
+               USB_DEVICE_ID_APPLE_MAGICMOUSE),
+         HID_BATTERY_QUIRK_IGNORE },
        { HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM,
                USB_DEVICE_ID_ELECOM_BM084),
          HID_BATTERY_QUIRK_IGNORE },

3. Build Ubuntu Kernel

Build by referring to this article.

Ubuntu Weekly Recipe --No. 526 How to easily build the latest kernel on Ubuntu

First, copy the config file from Ubuntu on the host to docker.

docker cp /boot/config-5.4.0-42-generic ubuntu:/tmp/

Move the copied configuration file on the docker container to reflect the settings.

mkdir ../build
cp /tmp/config-5.4.0-42-generic ../build/.config
scripts/config --file ../build/.config --disable DEBUG_INFO
make O=../build/ oldconfig

Build the kernel and modules.

time make -j 32 O=../build/ LOCALVERSION=-mt2patch

real    5m32.215s
user    140m10.856s
sys     16m43.152s

time make modules -j 32 O=../build/ LOCALVERSION=-mt2patch

real    0m27.762s
user    1m30.672s
sys     1m41.236s

time make bindeb-pkg -j 32 O=../build/ LOCALVERSION=-mt2patch

real    1m3.661s
user    4m49.134s
sys     2m14.784s

Ryzen 9 3950x is explosive ...

4. Install Ubuntu Kernel

As a result of building, the package is created in the directory one level above.

ls -l ../*.deb
-rw-r--r-- 1 root root 11424784 Aug 26 17:45 ../linux-headers-5.4.44-mt2patch_5.4.44-mt2patch-1_amd64.deb
-rw-r--r-- 1 root root 61014544 Aug 26 17:45 ../linux-image-5.4.44-mt2patch_5.4.44-mt2patch-1_amd64.deb
-rw-r--r-- 1 root root  1071376 Aug 26 17:45 ../linux-libc-dev_5.4.44-mt2patch-1_amd64.deb

Here, the file name is 5.4.44-mt2patch. The kernel config version is CONFIG_VERSION_SIGNATURE =" Ubuntu 5.4.0-42.46-generic 5.4.44 " Is it because it was?

Copy these to the host side and install.

docker cp ubuntu:/root/linux-headers-5.4.44-mt2patch_5.4.44-mt2patch-1_amd64.deb .
docker cp ubuntu:/root/linux-image-5.4.44-mt2patch_5.4.44-mt2patch-1_amd64.deb .
docker cp ubuntu:/root/linux-libc-dev_5.4.44-mt2patch-1_amd64.deb .

sudo apt install ./linux-headers-5.4.44-mt2patch_5.4.44-mt2patch-1_amd64.deb
sudo apt install ./linux-image-5.4.44-mt2patch_5.4.44-mt2patch-1_amd64.deb
sudo apt install ./linux-libc-dev_5.4.44-mt2patch-1_amd64.deb

accomplished. From now on, I hope the cursor doesn't freeze.

When you want to revert to the original kernel

When the kernel you built doesn't work as expected You will want to boot with the original kernel. In that case, modify / etc / default / grub.

sudo vim /etc/default/grub

The fix is to set GRUB_TIMEOUT_STYLE = menu to extend the timeout period. You can now select the kernel to use at boot time.

--- grub.ucf-dist       2020-08-02 19:43:53.512717712 +0900
+++ grub        2020-08-26 17:25:45.283739309 +0900
@@ -4,8 +4,9 @@
 #   info -f grub -n 'Simple configuration'

 GRUB_DEFAULT=0
-GRUB_TIMEOUT_STYLE=hidden
-GRUB_TIMEOUT=0
+#GRUB_TIMEOUT_STYLE=hidden
+GRUB_TIMEOUT_STYLE=menu
+GRUB_TIMEOUT=5
 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
 GRUB_CMDLINE_LINUX_DEFAULT=""
 GRUB_CMDLINE_LINUX=""

Update grub when the fix is complete.

sudo update-grub