The official Raspberry Pi touchscreen (the 7" model connected via the DSI port) does not operate when the KMS overlay is applied (as is the default on the Ubuntu Desktop for Raspberry Pi images). The display does operate on RaspiOS Bullseye, also running kernel 5.15, when the KMS overlay is used. Notably, the display does work on Ubuntu with no KMS overlay (legacy framebuffer), or with the FKMS ("fake" KMS) overlay.
The symptom is simply no output at all on the display. Sometimes there is the initial "rainbow" screen of the start4.elf bootloader, but then nothing. Notably this is *slightly* different to the Impish 5.13 kernel. On thata version, the DSI display also failed with the KMS overlay, but in that case there was an initial flashing cursor (presumably at the start of the initrd, perhaps on a leftover framebuffer?) which then disappears before anything is printed. On 5.15 there's nothing after the "rainbow".
The symptoms are the same on both armhf and arm64 images.
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: linux-raspi 5.15.0.1005.5
ProcVersionSignature: Ubuntu 5.15.0-1005.5-raspi 5.15.30
Uname: Linux 5.15.0-1005-raspi armv7l
AlsaVersion: Advanced Linux Sound Architecture Driver Version k5.15.0-1005-raspi.
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.11-0ubuntu82
Architecture: armhf
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC0', '/dev/snd/pcmC0D0p', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: N/A
Card0.Amixer.info: Error: [Errno 2] No such file or directory: 'amixer'
Card0.Amixer.values: Error: [Errno 2] No such file or directory: 'amixer'
CasperMD5CheckResult: unknown
Date: Wed Apr 27 10:04:10 2022
ImageMediaBuild: 20220419
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lspci-vt: -[0000:00]---00.0-[01]----00.0 VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller
Lsusb:
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 04d9:0006 Holtek Semiconductor, Inc. Wired Keyboard (78/79 key) [RPI Wired Keyboard 5]
Bus 001 Device 003: ID 05e3:0610 Genesys Logic, Inc. Hub
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
PciMultimedia:
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
LANG=C.UTF-8
SHELL=/bin/bash
ProcFB:
ProcKernelCmdLine: coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 smsc95xx.macaddr=DC:A6:32:33:F5:57 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 console=ttyS0,115200 dwc_otg.lpm_enable=0 console=tty1 root=LABEL=writable rootfstype=ext4 rootwait video=DSI-1:800x480@60,rotate=180 fixrtc quiet splash
RelatedPackageVersions:
linux-restricted-modules-5.15.0-1005-raspi N/A
linux-backports-modules-5.15.0-1005-raspi N/A
linux-firmware 20220329.git681281e4-0ubuntu1
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux-raspi
StagingDrivers: bcm2835_v4l2 bcm2835_isp vc_sm_cma bcm2835_codec bcm2835_mmal_vchiq snd_bcm2835
UpgradeStatus: No upgrade log present (probably fresh install)
acpidump:
Update: with kernel 5.19 in kinetic, the DSI touchscreen is now producing output, at least under the Pi Desktop image (I have yet to test the Server image). However, while the graphical output works, the touchscreen input doesn't. Furthermore, all rotation methods I've tried so far have failed (the gnome control center claims it's rotated, but doesn't do anything, the video= kernel cmdline parameter appears to be ignored, as is the legacy display_lcd_rotate config.txt variable although the last was to be expected).