few kms tests - dmesg-warn/dmesg-fail - DSB 0 timed out waiting for idle

http://gfx-ci.igk.intel.com/cibuglog-ng/testresult/1612359071?query_key=4c6ddea0acc8e44c0aa40942dc89925ce673701e

<7> [551.347577] i915 0000:00:02.0: [drm:verify_connector_state [i915]] [CONNECTOR:236:DP-1]
<7> [551.347964] i915 0000:00:02.0: [drm:intel_modeset_verify_crtc [i915]] [CRTC:80:pipe A]
<7> [551.351252] i915 0000:00:02.0: [drm:intel_modeset_verify_crtc [i915]] [CRTC:131:pipe B]
<7> [551.371620] [drm:eb_lookup_vmas [i915]] EINVAL at eb_validate_vma:508
<7> [551.372011] [drm:eb_lookup_vmas [i915]] EINVAL at eb_validate_vma:508
<7> [551.386275] i915 0000:00:02.0: [drm:intel_power_well_disable [i915]] disabling AUX_B
<7> [551.430497] [drm:eb_lookup_vmas [i915]] EINVAL at eb_validate_vma:508
<7> [551.430712] [drm:eb_lookup_vmas [i915]] EINVAL at eb_validate_vma:508
<3> [551.448162] i915 0000:00:02.0: [drm] *ERROR* [CRTC:131:pipe B] DSB 0 timed out waiting for idle (current head=0xfe2c9000, head=0x0, tail=0x880)
<7> [551.448319] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]] [CRTC:131:pipe B] DSB 0 commands {
<7> [551.448453] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000000: 0x00000100 0x01271b08 0x00000000 0x00000000
<7> [551.448572] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000010: 0x00000000 0x00000000 0x00000000 0x00000000
<7> [551.448686] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000020: 0x00000000 0x00000000 0x00000000 0x01f4a800
<7> [551.448806] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000030: 0x00010101 0x01f4a804 0x00020202 0x01f4a808
<7> [551.448921] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000040: 0x00030303 0x01f4a80c 0x00040404 0x01f4a810
<7> [551.449034] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000050: 0x00050505 0x01f4a814 0x00060606 0x01f4a818
<7> [551.449145] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000060: 0x00070707 0x01f4a81c 0x00080808 0x01f4a820
<7> [551.449271] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000070: 0x00090909 0x01f4a824 0x000a0a0a 0x01f4a828
<7> [551.449448] i915 0000:00:02.0: [drm:intel_dsb_wait [i915]]  0x00000080: 0x000b0b0b 0x01f4a82c 0x000c0c0c 0x01f4a830