Every day or so, I'll click something and my screens go blank for a second or two. dmesg complains about a lockup, and afterwards everything is painfully slow. (Even switching focus to other emacs windows takes a second or two.) Once this happens, if I restart X, I get a blank screen, although the mouse still works and I can switch VTs and use the console.
My userspace driver is xorg-x11-drv-ati-7.0.0-0.9.20121015gitbd9e2c064.fc18.src.rpm. I have Option "ColorTiling2D" "true", but I'm not sure this matters. lspci says: 08:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Caicos [Radeon HD 6450] [ 7508.750753] radeon 0000:08:00.0: GPU lockup CP stall for more than 5102593msec [ 7508.750757] radeon 0000:08:00.0: GPU lockup (waiting for 0x0000000000000155 last fence id 0x0000000000000154) [ 7508.751832] radeon 0000:08:00.0: Saved 71 dwords of commands on ring 0. [ 7508.751837] radeon 0000:08:00.0: GPU softreset: 0x00000007 [ 7508.762035] radeon 0000:08:00.0: GRBM_STATUS = 0xA0003828 [ 7508.762037] radeon 0000:08:00.0: GRBM_STATUS_SE0 = 0x00000007 [ 7508.762040] radeon 0000:08:00.0: GRBM_STATUS_SE1 = 0x00000007 [ 7508.762042] radeon 0000:08:00.0: SRBM_STATUS = 0x200400C0 [ 7508.762045] radeon 0000:08:00.0: R_008674_CP_STALLED_STAT1 = 0x00000000 [ 7508.762047] radeon 0000:08:00.0: R_008678_CP_STALLED_STAT2 = 0x00000000 [ 7508.762050] radeon 0000:08:00.0: R_00867C_CP_BUSY_STAT = 0x00000004 [ 7508.762053] radeon 0000:08:00.0: R_008680_CP_STAT = 0x80008647 [ 7508.762054] radeon 0000:08:00.0: GRBM_SOFT_RESET=0x00007F6B [ 7508.762109] radeon 0000:08:00.0: GRBM_STATUS = 0x00003828 [ 7508.762112] radeon 0000:08:00.0: GRBM_STATUS_SE0 = 0x00000007 [ 7508.762114] radeon 0000:08:00.0: GRBM_STATUS_SE1 = 0x00000007 [ 7508.762117] radeon 0000:08:00.0: SRBM_STATUS = 0x200400C0 [ 7508.762120] radeon 0000:08:00.0: R_008674_CP_STALLED_STAT1 = 0x00000000 [ 7508.762122] radeon 0000:08:00.0: R_008678_CP_STALLED_STAT2 = 0x00000000 [ 7508.762125] radeon 0000:08:00.0: R_00867C_CP_BUSY_STAT = 0x00000000 [ 7508.762127] radeon 0000:08:00.0: R_008680_CP_STAT = 0x00000000 [ 7508.762131] radeon 0000:08:00.0: R_00D034_DMA_STATUS_REG = 0x4448C156 [ 7508.762187] radeon 0000:08:00.0: R_00D034_DMA_STATUS_REG = 0x44C83D57 [ 7508.779603] radeon 0000:08:00.0: GPU reset succeeded, trying to resume [ 7508.798041] [drm] probing gen 2 caps for device 8086:1d1a = 2/0 [ 7508.798047] [drm] enabling PCIE gen 2 link speeds, disable with radeon.pcie_gen2=0 [ 7508.805050] [drm] PCIE GART of 512M enabled (table at 0x0000000000040000). [ 7508.805186] radeon 0000:08:00.0: WB enabled [ 7508.805189] radeon 0000:08:00.0: fence driver on ring 0 use gpu addr 0x0000000040000c00 and cpu addr 0xffff880442ddcc00 [ 7508.805190] radeon 0000:08:00.0: fence driver on ring 3 use gpu addr 0x0000000040000c0c and cpu addr 0xffff880442ddcc0c [ 7508.821692] [drm] ring test on 0 succeeded in 2 usecs [ 7508.821765] [drm] ring test on 3 succeeded in 1 usecs [ 7508.821845] [drm] ib test on ring 0 succeeded in 0 usecs [ 7508.821923] [drm] ib test on ring 3 succeeded in 1 usecs --Andy