[PATCH] drm/i915/execlists: Disable submission tasklet upon wedging

[PATCH] drm/i915/execlists: Disable submission tasklet upon wedging

[Chris Wilson]

If we declare the driver wedged before the GPU truly is, then we may see
the GPU complete some CS events following our cancellation. This leaves
us quite confused as we deleted all the bookkeeping and thus complain
about the inconsistent state.

We can just ignore the remaining events and let the GPU idle by not
feeding it, and so avoid trying to racily overwrite shared state. We
rely on there being a full GPU reset before unwedging, giving us the
opportunity to reset the shared state.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107188
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_lrc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8fd8de71c2b5..8aac7414c48b 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -810,6 +810,11 @@ static void reset_csb_pointers(struct intel_engine_execlists *execlists)
 	WRITE_ONCE(*execlists->csb_write, execlists->csb_write_reset);
 }
 
+static void nop_submission_tasklet(unsigned long data)
+{
+	/* The driver is wedged; don't process any more events. */
+}
+
 static void execlists_cancel_requests(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
@@ -869,6 +874,8 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
 	execlists->queue = RB_ROOT_CACHED;
 	GEM_BUG_ON(port_isset(execlists->port));
 
+	execlists->tasklet.func = nop_submission_tasklet;
+
 	spin_unlock_irqrestore(&engine->timeline.lock, flags);
 }
 
-- 
2.18.0

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[PATCH] drm/i915/execlists: Disable submission tasklet upon wedging

[Chris Wilson]

If we declare the driver wedged before the GPU truly is, then we may see
the GPU complete some CS events following our cancellation. This leaves
us quite confused as we deleted all the bookkeeping and thus complain
about the inconsistent state.

We can just ignore the remaining events and let the GPU idle by not
feeding it, and so avoid trying to racily overwrite shared state. We
rely on there being a full GPU reset before unwedging, giving us the
opportunity to reset the shared state.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107188
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_lrc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8fd8de71c2b5..6fef9d130d55 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -810,6 +810,11 @@ static void reset_csb_pointers(struct intel_engine_execlists *execlists)
 	WRITE_ONCE(*execlists->csb_write, execlists->csb_write_reset);
 }
 
+static void nop_submission_tasklet(unsigned long data)
+{
+	/* The driver is wedged; don't process any more events. */
+}
+
 static void execlists_cancel_requests(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
@@ -869,6 +874,9 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
 	execlists->queue = RB_ROOT_CACHED;
 	GEM_BUG_ON(port_isset(execlists->port));
 
+	GEM_BUG_ON(__tasklet_is_enabled(&execlists->tasklet));
+	execlists->tasklet.func = nop_submission_tasklet;
+
 	spin_unlock_irqrestore(&engine->timeline.lock, flags);
 }
 
-- 
2.18.0

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✓ Fi.CI.BAT: success for drm/i915/execlists: Disable submission tasklet upon wedging (rev2)

[Patchwork]

== Series Details ==

Series: drm/i915/execlists: Disable submission tasklet upon wedging (rev2)
URL   : https://patchwork.freedesktop.org/series/46542/
State : success

== Summary ==

= CI Bug Log - changes from CI_DRM_4489 -> Patchwork_9661 =

== Summary - SUCCESS ==

  No regressions found.

  External URL: https://patchwork.freedesktop.org/api/1.0/series/46542/revisions/2/mbox/

== Known issues ==

  Here are the changes found in Patchwork_9661 that come from known issues:

  === IGT changes ===

    ==== Issues hit ====

    igt@gem_exec_suspend@basic-s4-devices:
      fi-kbl-7500u:       PASS -> DMESG-WARN (fdo#105128, fdo#107139)

    igt@kms_flip@basic-flip-vs-modeset:
      fi-skl-6700hq:      PASS -> DMESG-WARN (fdo#105998) +1

    igt@kms_frontbuffer_tracking@basic:
      fi-hsw-peppy:       PASS -> DMESG-FAIL (fdo#102614, fdo#106103)

    igt@kms_pipe_crc_basic@suspend-read-crc-pipe-b:
      fi-skl-guc:         PASS -> FAIL (fdo#103191)

    
  fdo#102614 https://bugs.freedesktop.org/show_bug.cgi?id=102614
  fdo#103191 https://bugs.freedesktop.org/show_bug.cgi?id=103191
  fdo#105128 https://bugs.freedesktop.org/show_bug.cgi?id=105128
  fdo#105998 https://bugs.freedesktop.org/show_bug.cgi?id=105998
  fdo#106103 https://bugs.freedesktop.org/show_bug.cgi?id=106103
  fdo#107139 https://bugs.freedesktop.org/show_bug.cgi?id=107139


== Participating hosts (45 -> 42) ==

  Missing    (3): fi-ilk-m540 fi-byt-squawks fi-hsw-4200u 


== Build changes ==

    * Linux: CI_DRM_4489 -> Patchwork_9661

  CI_DRM_4489: d0b0c9150d280254d8ce7fcddaaf96132ac5ec62 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_4558: d8e97e1710b27a3931a1c53d1dd88c0e709c085b @ git://anongit.freedesktop.org/xorg/app/intel-gpu-tools
  Patchwork_9661: cdcfbcf65992c4335e0235fff8ceb0f22412cb7a @ git://anongit.freedesktop.org/gfx-ci/linux


== Linux commits ==

cdcfbcf65992 drm/i915/execlists: Disable submission tasklet upon wedging

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_9661/issues.html
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✓ Fi.CI.IGT: success for drm/i915/execlists: Disable submission tasklet upon wedging (rev2)

[Patchwork]

== Series Details ==

Series: drm/i915/execlists: Disable submission tasklet upon wedging (rev2)
URL   : https://patchwork.freedesktop.org/series/46542/
State : success

== Summary ==

= CI Bug Log - changes from CI_DRM_4489_full -> Patchwork_9661_full =

== Summary - WARNING ==

  Minor unknown changes coming with Patchwork_9661_full need to be verified
  manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in Patchwork_9661_full, please notify your bug team to allow them
  to document this new failure mode, which will reduce false positives in CI.

  

== Possible new issues ==

  Here are the unknown changes that may have been introduced in Patchwork_9661_full:

  === IGT changes ===

    ==== Warnings ====

    igt@gem_exec_schedule@deep-bsd1:
      shard-kbl:          SKIP -> PASS +1

    igt@gem_exec_schedule@deep-vebox:
      shard-kbl:          PASS -> SKIP

    igt@kms_vblank@pipe-a-wait-busy:
      shard-snb:          SKIP -> PASS +1

    
== Known issues ==

  Here are the changes found in Patchwork_9661_full that come from known issues:

  === IGT changes ===

    ==== Issues hit ====

    igt@gem_ctx_isolation@vcs0-s3:
      shard-kbl:          PASS -> INCOMPLETE (fdo#103665)

    igt@kms_flip@2x-flip-vs-expired-vblank:
      shard-hsw:          PASS -> FAIL (fdo#102887)

    igt@kms_flip@2x-plain-flip-ts-check:
      shard-glk:          PASS -> FAIL (fdo#100368)

    
    ==== Possible fixes ====

    igt@kms_flip@2x-dpms-vs-vblank-race:
      shard-hsw:          FAIL (fdo#103060) -> PASS

    igt@kms_flip@plain-flip-ts-check-interruptible:
      shard-glk:          FAIL (fdo#100368) -> PASS +1

    
  fdo#100368 https://bugs.freedesktop.org/show_bug.cgi?id=100368
  fdo#102887 https://bugs.freedesktop.org/show_bug.cgi?id=102887
  fdo#103060 https://bugs.freedesktop.org/show_bug.cgi?id=103060
  fdo#103665 https://bugs.freedesktop.org/show_bug.cgi?id=103665


== Participating hosts (5 -> 5) ==

  No changes in participating hosts


== Build changes ==

    * Linux: CI_DRM_4489 -> Patchwork_9661

  CI_DRM_4489: d0b0c9150d280254d8ce7fcddaaf96132ac5ec62 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_4558: d8e97e1710b27a3931a1c53d1dd88c0e709c085b @ git://anongit.freedesktop.org/xorg/app/intel-gpu-tools
  Patchwork_9661: cdcfbcf65992c4335e0235fff8ceb0f22412cb7a @ git://anongit.freedesktop.org/gfx-ci/linux
  piglit_4509: fdc5a4ca11124ab8413c7988896eec4c97336694 @ git://anongit.freedesktop.org/piglit

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_9661/shards.html
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