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* [CI 1/9] drm/i915: Drop posting reads to flush master interrupts
@ 2018-06-28 20:12 Chris Wilson
  2018-06-28 20:12 ` [CI 2/9] drm/i915/execlists: Pull submit after dequeue under timeline lock Chris Wilson
                   ` (10 more replies)
  0 siblings, 11 replies; 12+ messages in thread
From: Chris Wilson @ 2018-06-28 20:12 UTC (permalink / raw)
  To: intel-gfx

We do not need to do a posting read of our uncached mmio write to
re-enable the master interrupt lines after handling an interrupt, so
don't. This saves us a slow UC read before we can process the interrupt,
most noticeable in execlists where any stalls imposes extra latency on
GPU command execution.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjala <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 4be56aec99b3..02fe0d32382e 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2183,7 +2183,6 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg)
 
 		I915_WRITE(VLV_IER, ier);
 		I915_WRITE(VLV_MASTER_IER, MASTER_INTERRUPT_ENABLE);
-		POSTING_READ(VLV_MASTER_IER);
 
 		if (gt_iir)
 			snb_gt_irq_handler(dev_priv, gt_iir);
@@ -2268,7 +2267,6 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg)
 
 		I915_WRITE(VLV_IER, ier);
 		I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
-		POSTING_READ(GEN8_MASTER_IRQ);
 
 		gen8_gt_irq_handler(dev_priv, master_ctl, gt_iir);
 
@@ -2637,7 +2635,6 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg)
 	/* disable master interrupt before clearing iir  */
 	de_ier = I915_READ(DEIER);
 	I915_WRITE(DEIER, de_ier & ~DE_MASTER_IRQ_CONTROL);
-	POSTING_READ(DEIER);
 
 	/* Disable south interrupts. We'll only write to SDEIIR once, so further
 	 * interrupts will will be stored on its back queue, and then we'll be
@@ -2647,7 +2644,6 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg)
 	if (!HAS_PCH_NOP(dev_priv)) {
 		sde_ier = I915_READ(SDEIER);
 		I915_WRITE(SDEIER, 0);
-		POSTING_READ(SDEIER);
 	}
 
 	/* Find, clear, then process each source of interrupt */
@@ -2682,11 +2678,8 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg)
 	}
 
 	I915_WRITE(DEIER, de_ier);
-	POSTING_READ(DEIER);
-	if (!HAS_PCH_NOP(dev_priv)) {
+	if (!HAS_PCH_NOP(dev_priv))
 		I915_WRITE(SDEIER, sde_ier);
-		POSTING_READ(SDEIER);
-	}
 
 	/* IRQs are synced during runtime_suspend, we don't require a wakeref */
 	enable_rpm_wakeref_asserts(dev_priv);
-- 
2.18.0

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^ permalink raw reply related	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2018-06-29  1:09 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-06-28 20:12 [CI 1/9] drm/i915: Drop posting reads to flush master interrupts Chris Wilson
2018-06-28 20:12 ` [CI 2/9] drm/i915/execlists: Pull submit after dequeue under timeline lock Chris Wilson
2018-06-28 20:12 ` [CI 3/9] drm/i915/execlists: Pull CSB reset under the timeline.lock Chris Wilson
2018-06-28 20:12 ` [CI 4/9] drm/i915/execlists: Process one CSB update at a time Chris Wilson
2018-06-28 20:12 ` [CI 5/9] drm/i915/execlists: Unify CSB access pointers Chris Wilson
2018-06-28 20:12 ` [CI 6/9] drm/i915/execlists: Reset CSB write pointer after reset Chris Wilson
2018-06-28 20:12 ` [CI 7/9] drm/i915/execlists: Stop storing the CSB read pointer in the mmio register Chris Wilson
2018-06-28 20:12 ` [CI 8/9] drm/i915/execlists: Trust the CSB Chris Wilson
2018-06-28 20:12 ` [CI 9/9] drm/i915/execlists: Direct submission of new requests (avoid tasklet/ksoftirqd) Chris Wilson
2018-06-28 20:55 ` ✗ Fi.CI.CHECKPATCH: warning for series starting with [CI,1/9] drm/i915: Drop posting reads to flush master interrupts Patchwork
2018-06-28 21:10 ` ✓ Fi.CI.BAT: success " Patchwork
2018-06-29  1:09 ` ✓ Fi.CI.IGT: " Patchwork

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