[PATCH] drm/i915: Flush ggtt writes through the old fenced vma before changing fences

[PATCH] drm/i915: Flush ggtt writes through the old fenced vma before changing fences

[Chris Wilson]

This is a precautionary measure as I have no evidence to suggest we've
hit a bug here (I was hoping this might explain gdg's odd behaviour, but
alas), but given that we have a function to flush the ggtt writes it
seems prudent to use it prior to changing the fence register. Due to the
intrinsic nature of the GTT often operating as an independent mmio path,
we should not just rely on the write to the fence acting as a full flush
for GTT writes.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem_fence_reg.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_fence_reg.c b/drivers/gpu/drm/i915/i915_gem_fence_reg.c
index 012250f25255..b8338d75c6f3 100644
--- a/drivers/gpu/drm/i915/i915_gem_fence_reg.c
+++ b/drivers/gpu/drm/i915/i915_gem_fence_reg.c
@@ -230,10 +230,14 @@ static int fence_update(struct drm_i915_fence_reg *fence,
 	}
 
 	if (fence->vma) {
-		ret = i915_gem_active_retire(&fence->vma->last_fence,
-				      &fence->vma->obj->base.dev->struct_mutex);
+		struct i915_vma *old = fence->vma;
+
+		ret = i915_gem_active_retire(&old->last_fence,
+					     &old->obj->base.dev->struct_mutex);
 		if (ret)
 			return ret;
+
+		i915_vma_flush_writes(old);
 	}
 
 	if (fence->vma && fence->vma != vma) {
-- 
2.15.1

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✓ Fi.CI.BAT: success for drm/i915: Flush ggtt writes through the old fenced vma before changing fences

[Patchwork]

== Series Details ==

Series: drm/i915: Flush ggtt writes through the old fenced vma before changing fences
URL   : https://patchwork.freedesktop.org/series/37355/
State : success

== Summary ==

Series 37355v1 drm/i915: Flush ggtt writes through the old fenced vma before changing fences
https://patchwork.freedesktop.org/api/1.0/series/37355/revisions/1/mbox/

Test gem_mmap_gtt:
        Subgroup basic-small-bo-tiledx:
                fail       -> PASS       (fi-gdg-551) fdo#102575
Test kms_pipe_crc_basic:
        Subgroup suspend-read-crc-pipe-b:
                pass       -> INCOMPLETE (fi-snb-2520m) fdo#103713

fdo#102575 https://bugs.freedesktop.org/show_bug.cgi?id=102575
fdo#103713 https://bugs.freedesktop.org/show_bug.cgi?id=103713

fi-bdw-5557u     total:288  pass:267  dwarn:0   dfail:0   fail:0   skip:21  time:422s
fi-bdw-gvtdvm    total:288  pass:264  dwarn:0   dfail:0   fail:0   skip:24  time:427s
fi-blb-e6850     total:288  pass:223  dwarn:1   dfail:0   fail:0   skip:64  time:373s
fi-bsw-n3050     total:288  pass:242  dwarn:0   dfail:0   fail:0   skip:46  time:486s
fi-bwr-2160      total:288  pass:183  dwarn:0   dfail:0   fail:0   skip:105 time:281s
fi-bxt-dsi       total:288  pass:258  dwarn:0   dfail:0   fail:0   skip:30  time:482s
fi-bxt-j4205     total:288  pass:259  dwarn:0   dfail:0   fail:0   skip:29  time:482s
fi-byt-j1900     total:288  pass:253  dwarn:0   dfail:0   fail:0   skip:35  time:466s
fi-byt-n2820     total:288  pass:249  dwarn:0   dfail:0   fail:0   skip:39  time:457s
fi-cfl-s2        total:288  pass:262  dwarn:0   dfail:0   fail:0   skip:26  time:569s
fi-elk-e7500     total:224  pass:168  dwarn:10  dfail:0   fail:0   skip:45 
fi-gdg-551       total:288  pass:180  dwarn:0   dfail:0   fail:0   skip:108 time:277s
fi-glk-1         total:288  pass:260  dwarn:0   dfail:0   fail:0   skip:28  time:514s
fi-hsw-4770      total:288  pass:261  dwarn:0   dfail:0   fail:0   skip:27  time:390s
fi-hsw-4770r     total:288  pass:261  dwarn:0   dfail:0   fail:0   skip:27  time:407s
fi-ilk-650       total:288  pass:228  dwarn:0   dfail:0   fail:0   skip:60  time:414s
fi-ivb-3520m     total:288  pass:259  dwarn:0   dfail:0   fail:0   skip:29  time:459s
fi-ivb-3770      total:288  pass:255  dwarn:0   dfail:0   fail:0   skip:33  time:412s
fi-kbl-7500u     total:288  pass:263  dwarn:1   dfail:0   fail:0   skip:24  time:462s
fi-kbl-7560u     total:288  pass:269  dwarn:0   dfail:0   fail:0   skip:19  time:500s
fi-kbl-7567u     total:288  pass:268  dwarn:0   dfail:0   fail:0   skip:20  time:455s
fi-kbl-r         total:288  pass:261  dwarn:0   dfail:0   fail:0   skip:27  time:502s
fi-skl-6260u     total:288  pass:268  dwarn:0   dfail:0   fail:0   skip:20  time:427s
fi-skl-6600u     total:288  pass:261  dwarn:0   dfail:0   fail:0   skip:27  time:511s
fi-skl-6700hq    total:288  pass:262  dwarn:0   dfail:0   fail:0   skip:26  time:527s
fi-skl-6700k2    total:288  pass:264  dwarn:0   dfail:0   fail:0   skip:24  time:487s
fi-skl-6770hq    total:288  pass:268  dwarn:0   dfail:0   fail:0   skip:20  time:484s
fi-skl-guc       total:288  pass:260  dwarn:0   dfail:0   fail:0   skip:28  time:413s
fi-skl-gvtdvm    total:288  pass:265  dwarn:0   dfail:0   fail:0   skip:23  time:430s
fi-snb-2520m     total:245  pass:211  dwarn:0   dfail:0   fail:0   skip:33 
fi-snb-2600      total:288  pass:248  dwarn:0   dfail:0   fail:0   skip:40  time:396s
Blacklisted hosts:
fi-glk-dsi       total:288  pass:258  dwarn:0   dfail:0   fail:0   skip:30  time:476s

0edf4cc4e7c163fa61312f1708fc92284b855f8e drm-tip: 2018y-01m-30d-18h-33m-48s UTC integration manifest
ca3a3d8881e9 drm/i915: Flush ggtt writes through the old fenced vma before changing fences

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_7829/issues.html
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✗ Fi.CI.IGT: warning for drm/i915: Flush ggtt writes through the old fenced vma before changing fences

[Patchwork]

== Series Details ==

Series: drm/i915: Flush ggtt writes through the old fenced vma before changing fences
URL   : https://patchwork.freedesktop.org/series/37355/
State : warning

== Summary ==

Test kms_cursor_legacy:
        Subgroup 2x-long-flip-vs-cursor-legacy:
                fail       -> PASS       (shard-hsw)
Test perf_pmu:
        Subgroup frequency:
                fail       -> PASS       (shard-apl) fdo#104829
Test kms_atomic_transition:
        Subgroup 1x-modeset-transitions-nonblocking:
                pass       -> SKIP       (shard-snb)
Test kms_plane:
        Subgroup plane-position-hole-pipe-a-planes:
                pass       -> SKIP       (shard-snb)
Test kms_flip:
        Subgroup wf_vblank-ts-check-interruptible:
                fail       -> PASS       (shard-snb) fdo#100368

fdo#104829 https://bugs.freedesktop.org/show_bug.cgi?id=104829
fdo#100368 https://bugs.freedesktop.org/show_bug.cgi?id=100368

shard-apl        total:2838 pass:1752 dwarn:1   dfail:0   fail:21  skip:1064 time:12701s
shard-hsw        total:2838 pass:1736 dwarn:1   dfail:0   fail:10  skip:1090 time:12119s
shard-snb        total:2838 pass:1328 dwarn:1   dfail:0   fail:10  skip:1499 time:6655s
Blacklisted hosts:
shard-kbl        total:2824 pass:1859 dwarn:5   dfail:0   fail:23  skip:936 time:9591s

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_7829/shards.html
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Re: [PATCH] drm/i915: Flush ggtt writes through the old fenced vma before changing fences

[Lahtinen, Joonas]

On Tue, 2018-01-30 at 16:44 +0000, Chris Wilson wrote:
> This is a precautionary measure as I have no evidence to suggest we've
> hit a bug here (I was hoping this might explain gdg's odd behaviour, but
> alas), but given that we have a function to flush the ggtt writes it
> seems prudent to use it prior to changing the fence register. Due to the
> intrinsic nature of the GTT often operating as an independent mmio path,
> we should not just rely on the write to the fence acting as a full flush
> for GTT writes.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Regards, Joonas
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