I am unable to get accelerated graphics on my PowerMac G5 7,2 machine. I am seeing these errors in dmesg

[    7.167090] [drm] radeon: irq initialized.
[    7.167105] [drm] Loading R300 Microcode
[    7.226080] [drm] radeon: ring at 0x0000000090001000
[    7.373021] [drm:.r100_ring_test [radeon]] *ERROR* radeon: ring test failed (scratch(0x15E4)=0xCAFEDEAD)
[    7.373079] [drm:.r100_cp_init [radeon]] *ERROR* radeon: cp isn't working (-22).
[    7.373086] radeon 0000:f0:10.0: failed initializing CP (-22).
[    7.373089] radeon 0000:f0:10.0: Disabling GPU acceleration
[    7.519661] [drm:.r100_cp_fini [radeon]] *ERROR* Wait for CP idle timeout, shutting down CP.
[    7.519879] [drm] radeon: cp finalized