Comment 33 for bug 642421

Thanks. Actually error messages have disappeared for me as well with your workaround, but boot time is still quite long and I've lost my mouse pointer with gdm :(
I've got this trace in dmesg:

[ 51.864127] Modules linked in: rfcomm binfmt_misc sco bnep l2cap parport_pc ppdev joydev snd_hda_codec_si3054 snd_hda_codec_realtek arc4 snd_hda_intel radeon snd_hda_codec snd_hwdep snd_pcm iwl3945 snd_seq_midi snd_rawmidi ttm snd_seq_midi_event iwlcore snd_seq pcmcia drm_kms_helper mac80211 snd_timer gspca_m5602 btusb snd_seq_device gspca_main firewire_ohci drm bluetooth videodev v4l1_compat r8169 sdhci_pci yenta_socket intel_agp firewire_core sdhci mii snd psmouse pcmcia_rsrc crc_itu_t serio_raw cfg80211 pcmcia_core i2c_algo_bit soundcore video snd_page_alloc agpgart output asus_laptop sparse_keymap led_class lp parport
[ 51.864238] Pid: 1028, comm: Xorg Not tainted 2.6.35-22-generic #33-Ubuntu
[ 51.864243] Call Trace:
[ 51.864258] [<c014ac52>] warn_slowpath_common+0x72/0xa0
[ 51.864292] [<f8b8c2de>] ? radeon_fence_wait+0x23e/0x290 [radeon]
[ 51.864326] [<f8b8c2de>] ? radeon_fence_wait+0x23e/0x290 [radeon]
[ 51.864335] [<c014ad23>] warn_slowpath_fmt+0x33/0x40
[ 51.864369] [<f8b8c2de>] radeon_fence_wait+0x23e/0x290 [radeon]
[ 51.864380] [<c0165e10>] ? autoremove_wake_function+0x0/0x50
[ 51.864414] [<f8b8ca01>] radeon_sync_obj_wait+0x11/0x20 [radeon]
[ 51.864430] [<f8a39e67>] ttm_bo_wait+0xe7/0x180 [ttm]
[ 51.864469] [<f8ba2049>] radeon_gem_wait_idle_ioctl+0x89/0x110 [radeon]
[ 51.864505] [<f86ac98d>] drm_ioctl+0x1ad/0x430 [drm]
[ 51.864530] [<f8ba1fc0>] ? radeon_gem_wait_idle_ioctl+0x0/0x110 [radeon]
[ 51.864538] [<c010afb2>] ? restore_i387_xstate+0xe2/0x210
[ 51.864544] [<c0226622>] vfs_ioctl+0x32/0xb0
[ 51.864557] [<f86ac7e0>] ? drm_ioctl+0x0/0x430 [drm]
[ 51.864562] [<c0226eb9>] do_vfs_ioctl+0x79/0x2d0
[ 51.864567] [<c01021d6>] ? restore_sigcontext+0xc6/0xe0
[ 51.864571] [<c0227177>] sys_ioctl+0x67/0x80
[ 51.864577] [<c05c90a4>] syscall_call+0x7/0xb
[ 51.864580] ---[ end trace cb6f809ca6822860 ]---
[ 52.021556] Failed to wait GUI idle while programming pipes. Bad things might happen.