Adding some printks reveals it calls r100_init() -> radeon_irq_kms_init() -> drm_irq_install() -> drm_dev_to_irq() and that fails. So no IRQ, no KMS.
lspci does not show Interrupt like on some other PCI devices. /proc/interrupts obviously does not contain the irq since we do not register any yet.
There is no BIOS option of "Enable IRQ for VGA" or similar (BIOS is latest). Could this be the problem?
What can I do to get KMS working on this computer?
-- Meelis Roos (mroos@linux.ee)
Try booting with radeon.agp_mode=-1
radeon: `-1' invalid for parameter `agp_mode'
radeon.agpmode=-1
However, I think there are a number of places where we require interrupts that would need to be worked around (fences, display hotplug, pageflipping) if not interrupt is available.
I did dome more testing with different cards an got a surprise. The machine works fine with other AGP cards - one MX440 with nouvea, another RV100 QY and a R200. They do have interrupt in lspci -vvv output.
Why does this specific card not have its IRQ routed - card ROM problem?