Package: raspi-firmware Severity: normal Dear Maintainer,
I've installed a RPi 400 system using a regular build of Debian Installer (bookworm RC2), and have begun using the official RPi firmware (as distributed in the 'raspi-firmware' bookworm package - including bootcode.bin) to start the the kernel. During an X-based LXDE session, I see visual 'speckling' (static-like noise that blits across the lower half-or-so of the display, mostly with dark greenish and dark bluish pixels) when moving the mouse pointer. NOTE: There are _two_ micro-HDMI ports on the RPi 400. This problem only occurs when the HDMI cable is connected to the port closest to the keyboard indicator lights (capslock, numlock). The problem _does not_ occur when the HDMI cable is connected to the port closest to the USB-C power supply port. Repro details: Moving the pointer through particular areas of the display seem to cause the flickering/speckling more repeatably. The lower 40-or-so pixels of the screen in particular (where the LXDE menubar appears by defaul) seems to be a boundary that causes the problem fairly reliably. Note that when pointer/cursor movement _stops_, the visual corruption also stops occurring. In other words: the condition appears on-screen temporarily during the mouse pointer movement. Additional details: * The system is running Debian kernel 6.1.0-8 from linux-image-arm64 6.1.25-1 * The problem is also replicable using the latest '*.{elf,dat,bin}' files from the upstream raspberrypi/firmware version 1.20230405 release. * The devicetree 'compatible' entry for the gpu is: $ cat /proc/device-tree/gpu/compatible brcm,bcm2711-vc5 * The vc4 video driver appears to initialize fine according to dmesg (I don't see any errors). * The vc4 driver is in use as a framebuffer device, I think. $ dmesg --notime | grep -i vc4 | tail -n 2 [drm] Initialized vc4 0.0.0 20140616 for gpu on minor 1 vc4-drm gpu: [drm] fb0: vc4drmfb frame buffer device * I've attempted to use the 'config_hdmi_boost'[1] setting from the upstream firmware to resolve the problem, since it mentions speckling (in fact, it's where I learned the term 'speckling') specifically, but this has not had any effect. The documentation there does mention that the option is ignored on RPi4, and it seems possible that that may also apply to RPi400. * Reducing the resolution of the desktop does not reduce or eliminate the speckling. Thank you for any help / suggestions, James [1] - https://www.raspberrypi.com/documentation/computers/config_txt.html#config_hdmi_boost