[GEN9] Few tests - dmesg-warn - *ERROR* CPU pipe A FIFO underrun

https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_966/fi-cfl-8700k/igt@kms_flip_tiling@flip-change-tiling@hdmi-a-1-pipe-a-y-to-yf-ccs.html

Dmesg,
<6> [299.964063] [IGT] kms_flip_tiling: starting dynamic subtest HDMI-A-1-pipe-A-Y-to-Yf-CCS
<7> [299.967525] [drm:drm_mode_addfb2] [FB:127]
<7> [299.987373] [drm:drm_mode_addfb2] [FB:128]
<3> [299.991256] i915 0000:00:02.0: [drm] *ERROR* CPU pipe A FIFO underrun
<7> [299.991428] i915 0000:00:02.0: [drm:intel_fbc_underrun_work_fn [i915]] Disabling FBC due to FIFO underrun.
<7> [299.996928] i915 0000:00:02.0: [drm:__intel_fbc_disable [i915]] Disabling FBC on [PLANE:31:plane 1A]
<7> [300.013327] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]   level *wm0,*wm1,*wm2,*wm3,*wm4,*wm5,*wm6,*wm7, twm, swm, stwm -> *wm0,*wm1,*wm2,*wm3,*wm4,*wm5,*wm6,*wm7, twm, swm, stwm
<7> [300.013396] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]   lines    0,   2,   3,   3,   5,   6,   6,   7,   0,   0,    0 ->    0,  16,  16,  16,  16,  16,  16,  16,   0,   0,    0
<7> [300.013444] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]  blocks    8,  29,  40,  44,  80,  96,  98, 114,   0,   0,    0 ->  241, 241, 241, 241, 241, 241, 241, 241,   0,   0,    0
<7> [300.013491] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A] min_ddb    9,  30,  41,  45,  81,  97,  99, 115,   0,   0,    0 ->  242, 242, 242, 242, 242, 242, 242, 242,   0,   0,    0
<7> [300.047013] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]   level *wm0,*wm1,*wm2,*wm3,*wm4,*wm5,*wm6,*wm7, twm, swm, stwm -> *wm0,*wm1,*wm2,*wm3,*wm4,*wm5,*wm6,*wm7, twm, swm, stwm
<7> [300.047069] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]   lines    0,  16,  16,  16,  16,  16,  16,  16,   0,   0,    0 ->    0,  16,  16,  16,  16,  16,  16,  16,   0,   0,    0
<7> [300.047161] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]  blocks  241, 241, 241, 241, 241, 241, 241, 241,   0,   0,    0 ->  121, 241, 241, 241, 241, 241, 241, 241,   0,   0,    0
<7> [300.047227] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A] min_ddb  242, 242, 242, 242, 242, 242, 242, 242,   0,   0,    0 ->  122, 242, 242, 242, 242, 242, 242, 242,   0,   0,    0
<7> [300.063683] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]   level *wm0,*wm1,*wm2,*wm3,*wm4,*wm5,*wm6,*wm7, twm, swm, stwm -> *wm0,*wm1,*wm2,*wm3,*wm4,*wm5,*wm6,*wm7, twm, swm, stwm
<7> [300.063740] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]   lines    0,  16,  16,  16,  16,  16,  16,  16,   0,   0,    0 ->    0,  16,  16,  16,  16,  16,  16,  16,   0,   0,    0
<7> [300.063788] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A]  blocks  121, 241, 241, 241, 241, 241, 241, 241,   0,   0,    0 ->  241, 241, 241, 241, 241, 241, 241, 241,   0,   0,    0
<7> [300.063835] i915 0000:00:02.0: [drm:skl_compute_wm [i915]] [PLANE:31:plane 1A] min_ddb  122, 242, 242, 242, 242, 242, 242, 242,   0,   0,    0 ->  242, 242, 242, 242, 242, 242, 242, 242,   0,   0,    0