Bug 102373

FIFO under run now also on:
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3070/shard-snb4/igt@kms_chv_cursor_fail@pipe-B-256x256-bottom-edge.html

*** Bug 102371 has been marked as a duplicate of this bug. ***

According to Maarten same fix should help on here too:
https://bugs.freedesktop.org/show_bug.cgi?id=102675

Is this fixed by commit 3cf50c63a76177e0bbe0e46e1abe4eb263128ba4 ?
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Tue Sep 19 14:14:18 2017 +0200

    drm/i915: Unset legacy_cursor_update early in intel_atomic_commit, v3.

Maartens fix doesn't cover the full FIFO underrun issue on SNB-shards. 
See for example:
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3179/shard-snb4/igt@kms_properties@crtc-properties-legacy.html

Note:
for these tests:
igt@kms_busy@extended-modeset-hang-newfb-render-A
igt@kms_busy@extended-modeset-hang-newfb-render-B
igt@kms_busy@extended-modeset-hang-newfb-with-reset-render-A
igt@kms_busy@extended-modeset-hang-newfb-with-reset-render-B

the reproduction rate of FIFO underruns appear to be 100% on the SNB-shards.

There is also a trend that started at CI_DRM_3227 from that:
igt@kms_flip@vblank-vs-hang-interruptible
igt@kms_mmio_vs_cs_flip@setplane_vs_cs_flip

have failed all times:

https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3227/shard-snb2/igt@kms_flip@vblank-vs-hang-interruptible.html
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3227/shard-snb4/igt@kms_mmio_vs_cs_flip@setplane_vs_cs_flip.html

(In reply to Marta Löfstedt from comment #7)
> There is also a trend that started at CI_DRM_3227 from that:
> igt@kms_flip@vblank-vs-hang-interruptible
> igt@kms_mmio_vs_cs_flip@setplane_vs_cs_flip
> 
> have failed all times:
> 
> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3227/shard-snb2/
> igt@kms_flip@vblank-vs-hang-interruptible.html
> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3227/shard-snb4/
> igt@kms_mmio_vs_cs_flip@setplane_vs_cs_flip.html

This trend appear to have been stopped from: CI_DRM_3239

A new trend of 100% reproducibility on:
igt@kms_busy@extended-pageflip-hang-oldfb-render-B and 
igt@kms_cursor_crc@cursor-128x128-dpms

appear to have started at CI_DRM_3242:

https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3242/shard-snb5/igt@kms_busy@extended-pageflip-hang-oldfb-render-B.html
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3242/shard-snb4/igt@kms_cursor_crc@cursor-128x128-dpms.html

and is stable at hitting FIFO underrun until at least CI_DRM_3249.

I just noticed that igt@kms_busy@extended-pageflip-hang-oldfb-render-B and 
igt@kms_cursor_crc@cursor-128x128-dpms are scheduled in the same shard for all those runs. The re-randomization of which test goes into which shard is only done  when IGT is rebuilt. 

Note, for each CI_DRM_NNNN there is a shards.html, where easily can see which tests that are in which shards, example: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3246/shards.html

So, there is potentially some context leak causing this grouping of FIFO underruns being more probable when tests are run in the same shard.

https://patchwork.freedesktop.org/series/32197/

*** Bug 103376 has been marked as a duplicate of this bug. ***

both patches are now rb'd'

commit b6b178a77210055b153dbc175e4468bd3c7122df (HEAD -> drm-intel-next-queued, drm-intel/for-linux-next, drm-intel/drm-intel-next-queued)
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Thu Oct 19 17:13:41 2017 +0200

    drm/i915: Calculate ironlake intermediate watermarks correctly, v2.

commit 28283f4f359cd7cfa9e65457bb98c507a2cd0cd0                                                                                                                                                                                                                                
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>                                                                                                                                                                                                                  
Date:   Thu Oct 19 17:13:40 2017 +0200                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                               
    drm/i915: Do not rely on wm preservation for ILK watermarks

Patches integrated to CI_DRM_3289,

this will be interesting to follow. As long as I have been filing cibuglog I have averaged about 1 new occurrence of FIFO underrun on SNB a day. So, I have to wait a while before closing,

anyways:
igt@kms_busy@extended-modeset-hang-newfb-render-A
igt@kms_busy@extended-modeset-hang-newfb-render-B
igt@kms_busy@extended-modeset-hang-newfb-with-reset-render-A
igt@kms_busy@extended-modeset-hang-newfb-with-reset-render-B

are now green on CI_DRM_3289.

There has been on FIFO underruns on SNB since CI_DRM_3289 until CI_DRM_3304, I am closing this bug. Thanks for the fix Maarten.