after I reinstalled debian from bullseye to bookworm, my second display stopped working. I actually use 2 displays on both windows and mac osx. the machine is imac 27, with VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Broadway PRO [Mobility Radeon HD 5850]. I also tryed differente cable, but no luck. I checked dmesg:
[drm:radeon_pci_probe [radeon]] *ERROR* radeon kernel modesetting for R600 or later requires firmware installed
See https://wiki.debian.org/Firmware for information about missing firmware
I installed installed firmware-amd-graphics, but the main display stays black and works just second display. How can I solve the issue?
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