Comment 26 for bug 535640

The current (hanging) batchbuffer for this bug is (from running intel_error_decode on i915_error_state captured with drm-intel-next or 2.6.34-rcX kernel)

0x0ad96000: 0x09100000: MI_LOAD_SCAN_LINES_INCL
0x0ad96004: 0x00000384: dword 1
0x0ad96008: 0x09100000: MI_LOAD_SCAN_LINES_INCL
0x0ad9600c: 0x00000384: dword 1
0x0ad96010: 0x01800020: MI_WAIT_FOR_EVENT
0x0ad96014: HEAD 0x54f08806: XY_SRC_COPY_BLT (rgb enabled, alpha enabled, src tile 1, dst tile 1)
0x0ad96018: 0x03cc0600: format 8888, dst pitch 1536, clipping disabled
0x0ad9601c: 0x00000000: dst (0,0)
0x0ad96020: 0x038405a0: dst (1440,900)
0x0ad96024: 0x02522000: dst offset 0x02522000
0x0ad96028: 0x00000000: src (0,0)
0x0ad9602c: 0x00000600: src pitch 1536
0x0ad96030: 0x0360e000: src offset 0x0360e000
0x0ad96034: 0x02000000: MI_FLUSH
0x0ad96038: 0x00000000: MI_NOOP
0x0ad9603c: 0x05000000: MI_BATCH_BUFFER_END

Most of the 50+ automatically reported Ubuntu bug reports that are duplicates to this fail to record this batchbuffer with intel_gpu_dump. In the limited i915_error_state that is captured with the Ubuntu kernel, one can se IPEHR: 0x01800020 (header of last instruction) in all those reports.

This last instruction MI_WAIT_FOR_EVENT (Display Pipe B Scan Line Window Wait Enable) may (or may not) be related to the lines in dmesg output:

[ 3188.322798] [drm:gm45_get_vblank_counter], trying to get vblank count for disabled pipe 0
[ 3188.532922] [drm:gm45_get_vblank_counter], trying to get vblank count for disabled pipe 1