Comment 11 for bug 1850876

short version:

With raspberry pi 4:
your binaries applied (https://people.canonical.com/~hwang4/v3d-fix/)
The screen flickers then blanks
I installed an built the latest mesa
The screen flickers then blanks
Back to the raspberry pi kernel (4.19)
Which still works...

long version:

downloaded ubuntu-19.10-preinstalled-server-arm64+raspi3.img and restored it to sdcard

sudo apt update
sudo apt upgrade
sudo apt install ubuntu-desktop

wget https://people.canonical.com/~hwang4/v3d-fix/linux-buildinfo-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb
wget https://people.canonical.com/~hwang4/v3d-fix/linux-headers-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb
wget https://people.canonical.com/~hwang4/v3d-fix/linux-image-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb
wget https://people.canonical.com/~hwang4/v3d-fix/linux-modules-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb

sudo dpkg -i linux-modules-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb
sudo dpkg -i linux-image-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb
sudo dpkg -i linux-buildinfo-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb

sudo dpkg -i linux-headers-5.3.0-1013-raspi2_5.3.0-1013.15+v3d_arm64.deb
 linux-headers-5.3.0-1013-raspi2 depends on linux-raspi2-headers-5.3.0-1013; however:
  Package linux-raspi2-headers-5.3.0-1013 is not installed.
sudo apt --fix-broken install
The following packages will be REMOVED:
  linux-headers-5.3.0-1013-raspi2

sudo reboot
sudo apt-get install mesa-utils

glxinfo -B

name of display: :0
display: :0 screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: Broadcom (0x14e4)
    Device: V3D 4.2 (0xffffffff)
    Version: 19.2.1
    Accelerated: yes
    Video memory: 3791MB
    Unified memory: yes
    Preferred profile: compat (0x2)
    Max core profile version: 0.0
    Max compat profile version: 2.1
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.0
OpenGL vendor string: Broadcom
OpenGL renderer string: V3D 4.2
OpenGL version string: 2.1 Mesa 19.2.1
OpenGL shading language version string: 1.20

OpenGL ES profile version string: OpenGL ES 3.0 Mesa 19.2.1
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00

glxgears

Running synchronized to the vertical refresh. The framerate should be
approximately the same as the monitor refresh rate.
348 frames in 5.0 seconds = 69.440 FPS
247 frames in 5.0 seconds = 49.358 FPS
301 frames in 5.0 seconds = 60.029 FPS
301 frames in 5.0 seconds = 60.019 FPS
300 frames in 5.0 seconds = 59.999 FPS
300 frames in 5.0 seconds = 59.992 FPS
256 frames in 5.0 seconds = 51.041 FPS
300 frames in 5.0 seconds = 59.989 FPS
301 frames in 5.0 seconds = 60.011 FPS
X connection to :0 broken (explicit kill or server shutdown).

Eventually screen starts to flicker then blanks...
built and installed latest mesa - no change

sudo nano /etc/apt/sources.list (commented in all sources)
sudo apt update
sudo apt-get build-dep mesa

mkdir git
cd git
sudo apt-get build-dep mesa
sudo apt-get install -y pkg-config bison flex

git clone https://gitlab.freedesktop.org/mesa/drm.git
cd drm
meson build --prefix=/usr --libdir=/usr/lib/aarch64-linux-gnu
ninja -C build
sudo ninja -C build install
cd ..

git clone https://gitlab.freedesktop.org/mesa/mesa.git
cd mesa
meson build \
    --prefix=/usr \
    --libdir=/usr/lib/aarch64-linux-gnu \
    -Dbuildtype=release \
    -Dplatforms=x11,drm,surfaceless \
    -Ddri-drivers= \
    -Dgallium-drivers=vc4,v3d,kmsro
ninja -C build
sudo ninja -C build install

sudo reboot

flickers and then blanks :(