[PATCH 1/2] drm/i915: Drop racy markup of missed-irqs from idle-worker

[PATCH 1/2] drm/i915: Drop racy markup of missed-irqs from idle-worker

[Chris Wilson]

During the idle-worker we disable the hangcheck and so kick any waiters
that should have been completed (since the GPU is now idle). Unlike the
hangcheck, we do not take any care to avoid the race between the irq
handler and ourselves, and so it is possible for us to declare a missed
interrupt even as the bottom-half is being scheduled to run. Let's
ignore this race to stop a potential false-positive error.

References: https://bugs.freedesktop.org/show_bug.cgi?id=96974
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 40047eb48826..9e826585edb2 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2706,10 +2706,9 @@ i915_gem_idle_work_handler(struct work_struct *work)
 	rearm_hangcheck = false;
 
 	stuck_engines = intel_kick_waiters(dev_priv);
-	if (unlikely(stuck_engines)) {
-		DRM_DEBUG_DRIVER("kicked stuck waiters...missed irq\n");
-		dev_priv->gpu_error.missed_irq_rings |= stuck_engines;
-	}
+	if (unlikely(stuck_engines))
+		DRM_DEBUG_DRIVER("kicked stuck waiters (%x)...missed irq?\n",
+				 stuck_engines);
 
 	if (INTEL_GEN(dev_priv) >= 6)
 		gen6_rps_idle(dev_priv);
-- 
2.8.1

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[PATCH 2/2] drm/i915: Update the breadcrumb interrupt counter before enabling

[Chris Wilson]

In order to close a race with a long running hangcheck comparing a stale
interrupt counter with a just started waiter, we need to first bump the
counter as we start the fresh wait.

References: https://bugs.freedesktop.org/show_bug.cgi?id=96974
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_breadcrumbs.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index f0b56e3f4abe..d893ccdd62ac 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -51,6 +51,13 @@ static void irq_enable(struct intel_engine_cs *engine)
 	 */
 	engine->breadcrumbs.irq_posted = true;
 
+	/* Make sure the current hangcheck doesn't falsely accuse a just
+	 * started irq handler from missing an interrupt (because the
+	 * interrupt count still matches the stale value from when
+	 * the irq handler was disabled, many hangchecks ago).
+	 */
+	engine->breadcrumbs.irq_wakeups++;
+
 	spin_lock_irq(&engine->i915->irq_lock);
 	engine->irq_enable(engine);
 	spin_unlock_irq(&engine->i915->irq_lock);
-- 
2.8.1

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✗ Ro.CI.BAT: failure for series starting with [1/2] drm/i915: Drop racy markup of missed-irqs from idle-worker

[Patchwork]

== Series Details ==

Series: series starting with [1/2] drm/i915: Drop racy markup of missed-irqs from idle-worker
URL   : https://patchwork.freedesktop.org/series/10104/
State : failure

== Summary ==

Series 10104v1 Series without cover letter
http://patchwork.freedesktop.org/api/1.0/series/10104/revisions/1/mbox

Test gem_exec_suspend:
        Subgroup basic-s3:
                pass       -> INCOMPLETE (fi-skl-i7-6700k)
Test gem_sync:
        Subgroup basic-store-each:
                pass       -> DMESG-FAIL (ro-bdw-i7-5600u)
Test kms_flip:
        Subgroup basic-flip-vs-wf_vblank:
                pass       -> FAIL       (ro-hsw-i7-4770r)
Test kms_pipe_crc_basic:
        Subgroup suspend-read-crc-pipe-c:
                pass       -> INCOMPLETE (fi-hsw-i7-4770k)

fi-hsw-i7-4770k  total:208  pass:189  dwarn:0   dfail:0   fail:0   skip:18 
fi-kbl-qkkr      total:244  pass:179  dwarn:28  dfail:1   fail:8   skip:28 
fi-skl-i5-6260u  total:244  pass:224  dwarn:0   dfail:0   fail:8   skip:12 
fi-skl-i7-6700k  total:107  pass:84   dwarn:0   dfail:0   fail:0   skip:22 
fi-snb-i7-2600   total:244  pass:196  dwarn:0   dfail:0   fail:8   skip:40 
ro-bdw-i5-5250u  total:244  pass:219  dwarn:4   dfail:0   fail:8   skip:13 
ro-bdw-i7-5557U  total:244  pass:220  dwarn:3   dfail:0   fail:8   skip:13 
ro-bdw-i7-5600u  total:244  pass:203  dwarn:0   dfail:1   fail:8   skip:32 
ro-bsw-n3050     total:218  pass:173  dwarn:0   dfail:0   fail:2   skip:42 
ro-byt-n2820     total:244  pass:197  dwarn:0   dfail:0   fail:9   skip:38 
ro-hsw-i3-4010u  total:244  pass:212  dwarn:0   dfail:0   fail:8   skip:24 
ro-hsw-i7-4770r  total:244  pass:211  dwarn:0   dfail:0   fail:9   skip:24 
ro-ilk-i7-620lm  total:244  pass:172  dwarn:0   dfail:0   fail:9   skip:63 
ro-ilk1-i5-650   total:239  pass:172  dwarn:0   dfail:0   fail:9   skip:58 
ro-ivb-i7-3770   total:244  pass:203  dwarn:0   dfail:0   fail:8   skip:33 
ro-skl3-i5-6260u total:244  pass:224  dwarn:0   dfail:0   fail:8   skip:12 
ro-snb-i7-2620M  total:244  pass:193  dwarn:0   dfail:0   fail:9   skip:42 

Results at /archive/results/CI_IGT_test/RO_Patchwork_1552/

621e9dc drm-intel-nightly: 2016y-07m-20d-19h-19m-37s UTC integration manifest
999bd7b drm/i915: Update the breadcrumb interrupt counter before enabling
6775d84 drm/i915: Drop racy markup of missed-irqs from idle-worker

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