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* [PATCH] drm/i915/gen6: Flush RING_IMR changes before changing the global GT IMR
@ 2019-01-02 16:35 Chris Wilson
  2019-01-02 17:10 ` ✓ Fi.CI.BAT: success for " Patchwork
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: Chris Wilson @ 2019-01-02 16:35 UTC (permalink / raw)
  To: intel-gfx

On Baytail, notably, we can still detect missed interrupt syndrome
(where we never spot a completed request). In this case, it can be
alleviated by always keeping the interrupt unmasked, implying that the
interrupt is being lost in the window after modifying the IMR. (This is
the reason we still have the posting reads on enable_irq, if we remove
them we miss interrupts!) Having narrowed the issue down to the IMR,
rather than keeping it always enabled, applying the usual posting
read/flush of the RING_IMR before unmasking the GT IMR also seems to
prevent the missed interrupt. So be it.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 8967dcb5f58f..3d5d6b908148 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -974,6 +974,10 @@ gen6_irq_enable(struct intel_engine_cs *engine)
 	I915_WRITE_IMR(engine,
 		       ~(engine->irq_enable_mask |
 			 engine->irq_keep_mask));
+
+	/* Flush/delay to ensure the RING_IMR is active before the GT IMR */
+	POSTING_READ_FW(RING_IMR(engine->mmio_base));
+
 	gen5_enable_gt_irq(dev_priv, engine->irq_enable_mask);
 }
 
-- 
2.20.1

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^ permalink raw reply related	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2019-01-03 10:40 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2019-01-02 16:35 [PATCH] drm/i915/gen6: Flush RING_IMR changes before changing the global GT IMR Chris Wilson
2019-01-02 17:10 ` ✓ Fi.CI.BAT: success for " Patchwork
2019-01-02 18:24 ` ✓ Fi.CI.IGT: " Patchwork
2019-01-03 10:25 ` [PATCH] " Mika Kuoppala
2019-01-03 10:39   ` Chris Wilson

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