drm/i915: Move the get/put irq locking into the caller

With only a single callsite for intel_engine_cs->irq_get and ->irq_put,
we can reduce the code size by moving the common preamble into the
caller, and we can also eliminate the reference counting.

For completeness, as we are no longer doing reference counting on irq,
rename the get/put vfunctions to enable/disable respectively and are
able to review the use of posting reads. We only require the
serialisation with hardware when enabling the interrupt (i.e. so we
cannot miss an interrupt by going to sleep before the hardware truly
enables it).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467390209-3576-18-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_irq.c

@@ -259,12 +259,12 @@ static void ilk_update_gt_irq(struct drm_i915_private *dev_priv,
 	dev_priv->gt_irq_mask &= ~interrupt_mask;
 	dev_priv->gt_irq_mask |= (~enabled_irq_mask & interrupt_mask);
 	I915_WRITE(GTIMR, dev_priv->gt_irq_mask);
-	POSTING_READ(GTIMR);
 }
 
 void gen5_enable_gt_irq(struct drm_i915_private *dev_priv, uint32_t mask)
 {
 	ilk_update_gt_irq(dev_priv, mask, mask);
+	POSTING_READ_FW(GTIMR);
 }
 
 void gen5_disable_gt_irq(struct drm_i915_private *dev_priv, uint32_t mask)
@@ -2819,9 +2819,9 @@ ring_idle(struct intel_engine_cs *engine, u32 seqno)
 }
 
 static bool
-ipehr_is_semaphore_wait(struct drm_i915_private *dev_priv, u32 ipehr)
+ipehr_is_semaphore_wait(struct intel_engine_cs *engine, u32 ipehr)
 {
-	if (INTEL_GEN(dev_priv) >= 8) {
+	if (INTEL_GEN(engine->i915) >= 8) {
 		return (ipehr >> 23) == 0x1c;
 	} else {
 		ipehr &= ~MI_SEMAPHORE_SYNC_MASK;
@@ -2892,7 +2892,7 @@ semaphore_waits_for(struct intel_engine_cs *engine, u32 *seqno)
 		return NULL;
 
 	ipehr = I915_READ(RING_IPEHR(engine->mmio_base));
-	if (!ipehr_is_semaphore_wait(engine->i915, ipehr))
+	if (!ipehr_is_semaphore_wait(engine, ipehr))
 		return NULL;
 
 	/*

drivers/gpu/drm/i915/intel_breadcrumbs.c

@@ -50,12 +50,18 @@ static void irq_enable(struct intel_engine_cs *engine)
 	 * just in case.
 	 */
 	engine->irq_posted = true;
-	WARN_ON(!engine->irq_get(engine));
+
+	spin_lock_irq(&engine->i915->irq_lock);
+	engine->irq_enable(engine);
+	spin_unlock_irq(&engine->i915->irq_lock);
 }
 
 static void irq_disable(struct intel_engine_cs *engine)
 {
-	engine->irq_put(engine);
+	spin_lock_irq(&engine->i915->irq_lock);
+	engine->irq_disable(engine);
+	spin_unlock_irq(&engine->i915->irq_lock);
+
 	engine->irq_posted = false;
 }
 

drivers/gpu/drm/i915/intel_lrc.c

@@ -1617,36 +1617,18 @@ static int gen8_emit_bb_start(struct drm_i915_gem_request *req,
 	return 0;
 }
 
-static bool gen8_logical_ring_get_irq(struct intel_engine_cs *engine)
+static void gen8_logical_ring_enable_irq(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
-
-	if (WARN_ON(!intel_irqs_enabled(dev_priv)))
-		return false;
-
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (engine->irq_refcount++ == 0) {
-		I915_WRITE_IMR(engine,
-			       ~(engine->irq_enable_mask | engine->irq_keep_mask));
-		POSTING_READ(RING_IMR(engine->mmio_base));
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
-
-	return true;
+	I915_WRITE_IMR(engine,
+		       ~(engine->irq_enable_mask | engine->irq_keep_mask));
+	POSTING_READ_FW(RING_IMR(engine->mmio_base));
 }
 
-static void gen8_logical_ring_put_irq(struct intel_engine_cs *engine)
+static void gen8_logical_ring_disable_irq(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
-
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (--engine->irq_refcount == 0) {
-		I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
-		POSTING_READ(RING_IMR(engine->mmio_base));
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
+	I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
 }
 
 static int gen8_emit_flush(struct drm_i915_gem_request *request,
@@ -1966,8 +1948,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
 	engine->init_hw = gen8_init_common_ring;
 	engine->emit_request = gen8_emit_request;
 	engine->emit_flush = gen8_emit_flush;
-	engine->irq_get = gen8_logical_ring_get_irq;
-	engine->irq_put = gen8_logical_ring_put_irq;
+	engine->irq_enable = gen8_logical_ring_enable_irq;
+	engine->irq_disable = gen8_logical_ring_disable_irq;
 	engine->emit_bb_start = gen8_emit_bb_start;
 	if (IS_BXT_REVID(engine->i915, 0, BXT_REVID_A1))
 		engine->irq_seqno_barrier = bxt_a_seqno_barrier;

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1636,103 +1636,54 @@ gen6_seqno_barrier(struct intel_engine_cs *engine)
 	spin_unlock_irq(&dev_priv->uncore.lock);
 }
 
-static bool
-gen5_ring_get_irq(struct intel_engine_cs *engine)
+static void
+gen5_irq_enable(struct intel_engine_cs *engine)
 {
-	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
-
-	if (WARN_ON(!intel_irqs_enabled(dev_priv)))
-		return false;
-
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (engine->irq_refcount++ == 0)
-		gen5_enable_gt_irq(dev_priv, engine->irq_enable_mask);
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
-
-	return true;
+	gen5_enable_gt_irq(engine->i915, engine->irq_enable_mask);
 }
 
 static void
-gen5_ring_put_irq(struct intel_engine_cs *engine)
+gen5_irq_disable(struct intel_engine_cs *engine)
 {
-	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
-
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (--engine->irq_refcount == 0)
-		gen5_disable_gt_irq(dev_priv, engine->irq_enable_mask);
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
+	gen5_disable_gt_irq(engine->i915, engine->irq_enable_mask);
 }
 
-static bool
-i9xx_ring_get_irq(struct intel_engine_cs *engine)
+static void
+i9xx_irq_enable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
-
-	if (!intel_irqs_enabled(dev_priv))
-		return false;
-
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (engine->irq_refcount++ == 0) {
-		dev_priv->irq_mask &= ~engine->irq_enable_mask;
-		I915_WRITE(IMR, dev_priv->irq_mask);
-		POSTING_READ(IMR);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 
-	return true;
+	dev_priv->irq_mask &= ~engine->irq_enable_mask;
+	I915_WRITE(IMR, dev_priv->irq_mask);
+	POSTING_READ_FW(RING_IMR(engine->mmio_base));
 }
 
 static void
-i9xx_ring_put_irq(struct intel_engine_cs *engine)
+i9xx_irq_disable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (--engine->irq_refcount == 0) {
-		dev_priv->irq_mask |= engine->irq_enable_mask;
-		I915_WRITE(IMR, dev_priv->irq_mask);
-		POSTING_READ(IMR);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
+	dev_priv->irq_mask |= engine->irq_enable_mask;
+	I915_WRITE(IMR, dev_priv->irq_mask);
 }
 
-static bool
-i8xx_ring_get_irq(struct intel_engine_cs *engine)
+static void
+i8xx_irq_enable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
 
-	if (!intel_irqs_enabled(dev_priv))
-		return false;
-
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (engine->irq_refcount++ == 0) {
-		dev_priv->irq_mask &= ~engine->irq_enable_mask;
-		I915_WRITE16(IMR, dev_priv->irq_mask);
-		POSTING_READ16(IMR);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
-
-	return true;
+	dev_priv->irq_mask &= ~engine->irq_enable_mask;
+	I915_WRITE16(IMR, dev_priv->irq_mask);
+	POSTING_READ16(RING_IMR(engine->mmio_base));
 }
 
 static void
-i8xx_ring_put_irq(struct intel_engine_cs *engine)
+i8xx_irq_disable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (--engine->irq_refcount == 0) {
-		dev_priv->irq_mask |= engine->irq_enable_mask;
-		I915_WRITE16(IMR, dev_priv->irq_mask);
-		POSTING_READ16(IMR);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
+	dev_priv->irq_mask |= engine->irq_enable_mask;
+	I915_WRITE16(IMR, dev_priv->irq_mask);
 }
 
 static int
@@ -1773,122 +1724,74 @@ i9xx_add_request(struct drm_i915_gem_request *req)
 	return 0;
 }
 
-static bool
-gen6_ring_get_irq(struct intel_engine_cs *engine)
+static void
+gen6_irq_enable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
-
-	if (WARN_ON(!intel_irqs_enabled(dev_priv)))
-		return false;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (engine->irq_refcount++ == 0) {
-		if (HAS_L3_DPF(dev_priv) && engine->id == RCS)
-			I915_WRITE_IMR(engine,
-				       ~(engine->irq_enable_mask |
-					 GT_PARITY_ERROR(dev_priv)));
-		else
-			I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
-		gen5_enable_gt_irq(dev_priv, engine->irq_enable_mask);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
-
-	return true;
+	if (HAS_L3_DPF(dev_priv) && engine->id == RCS)
+		I915_WRITE_IMR(engine,
+			       ~(engine->irq_enable_mask |
+				 GT_PARITY_ERROR(dev_priv)));
+	else
+		I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
+	gen5_enable_gt_irq(dev_priv, engine->irq_enable_mask);
 }
 
 static void
-gen6_ring_put_irq(struct intel_engine_cs *engine)
+gen6_irq_disable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (--engine->irq_refcount == 0) {
-		if (HAS_L3_DPF(dev_priv) && engine->id == RCS)
-			I915_WRITE_IMR(engine, ~GT_PARITY_ERROR(dev_priv));
-		else
-			I915_WRITE_IMR(engine, ~0);
-		gen5_disable_gt_irq(dev_priv, engine->irq_enable_mask);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
+	if (HAS_L3_DPF(dev_priv) && engine->id == RCS)
+		I915_WRITE_IMR(engine, ~GT_PARITY_ERROR(dev_priv));
+	else
+		I915_WRITE_IMR(engine, ~0);
+	gen5_disable_gt_irq(dev_priv, engine->irq_enable_mask);
 }
 
-static bool
-hsw_vebox_get_irq(struct intel_engine_cs *engine)
+static void
+hsw_vebox_irq_enable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
-
-	if (WARN_ON(!intel_irqs_enabled(dev_priv)))
-		return false;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (engine->irq_refcount++ == 0) {
-		I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
-		gen6_enable_pm_irq(dev_priv, engine->irq_enable_mask);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
-
-	return true;
+	I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
+	gen6_enable_pm_irq(dev_priv, engine->irq_enable_mask);
 }
 
 static void
-hsw_vebox_put_irq(struct intel_engine_cs *engine)
+hsw_vebox_irq_disable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (--engine->irq_refcount == 0) {
-		I915_WRITE_IMR(engine, ~0);
-		gen6_disable_pm_irq(dev_priv, engine->irq_enable_mask);
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
+	I915_WRITE_IMR(engine, ~0);
+	gen6_disable_pm_irq(dev_priv, engine->irq_enable_mask);
 }
 
-static bool
-gen8_ring_get_irq(struct intel_engine_cs *engine)
+static void
+gen8_irq_enable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
 
-	if (WARN_ON(!intel_irqs_enabled(dev_priv)))
-		return false;
-
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (engine->irq_refcount++ == 0) {
-		if (HAS_L3_DPF(dev_priv) && engine->id == RCS) {
-			I915_WRITE_IMR(engine,
-				       ~(engine->irq_enable_mask |
-					 GT_RENDER_L3_PARITY_ERROR_INTERRUPT));
-		} else {
-			I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
-		}
-		POSTING_READ(RING_IMR(engine->mmio_base));
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
-
-	return true;
+	if (HAS_L3_DPF(dev_priv) && engine->id == RCS)
+		I915_WRITE_IMR(engine,
+			       ~(engine->irq_enable_mask |
+				 GT_RENDER_L3_PARITY_ERROR_INTERRUPT));
+	else
+		I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
+	POSTING_READ_FW(RING_IMR(engine->mmio_base));
 }
 
 static void
-gen8_ring_put_irq(struct intel_engine_cs *engine)
+gen8_irq_disable(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned long flags;
 
-	spin_lock_irqsave(&dev_priv->irq_lock, flags);
-	if (--engine->irq_refcount == 0) {
-		if (HAS_L3_DPF(dev_priv) && engine->id == RCS) {
-			I915_WRITE_IMR(engine,
-				       ~GT_RENDER_L3_PARITY_ERROR_INTERRUPT);
-		} else {
-			I915_WRITE_IMR(engine, ~0);
-		}
-		POSTING_READ(RING_IMR(engine->mmio_base));
-	}
-	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
+	if (HAS_L3_DPF(dev_priv) && engine->id == RCS)
+		I915_WRITE_IMR(engine,
+			       ~GT_RENDER_L3_PARITY_ERROR_INTERRUPT);
+	else
+		I915_WRITE_IMR(engine, ~0);
 }
 
 static int
@@ -2909,23 +2812,23 @@ static void intel_ring_init_irq(struct drm_i915_private *dev_priv,
 				struct intel_engine_cs *engine)
 {
 	if (INTEL_GEN(dev_priv) >= 8) {
-		engine->irq_get = gen8_ring_get_irq;
-		engine->irq_put = gen8_ring_put_irq;
+		engine->irq_enable = gen8_irq_enable;
+		engine->irq_disable = gen8_irq_disable;
 		engine->irq_seqno_barrier = gen6_seqno_barrier;
 	} else if (INTEL_GEN(dev_priv) >= 6) {
-		engine->irq_get = gen6_ring_get_irq;
-		engine->irq_put = gen6_ring_put_irq;
+		engine->irq_enable = gen6_irq_enable;
+		engine->irq_disable = gen6_irq_disable;
 		engine->irq_seqno_barrier = gen6_seqno_barrier;
 	} else if (INTEL_GEN(dev_priv) >= 5) {
-		engine->irq_get = gen5_ring_get_irq;
-		engine->irq_put = gen5_ring_put_irq;
+		engine->irq_enable = gen5_irq_enable;
+		engine->irq_disable = gen5_irq_disable;
 		engine->irq_seqno_barrier = gen5_seqno_barrier;
 	} else if (INTEL_GEN(dev_priv) >= 3) {
-		engine->irq_get = i9xx_ring_get_irq;
-		engine->irq_put = i9xx_ring_put_irq;
+		engine->irq_enable = i9xx_irq_enable;
+		engine->irq_disable = i9xx_irq_disable;
 	} else {
-		engine->irq_get = i8xx_ring_get_irq;
-		engine->irq_put = i8xx_ring_put_irq;
+		engine->irq_enable = i8xx_irq_enable;
+		engine->irq_disable = i8xx_irq_disable;
 	}
 }
 
@@ -3115,8 +3018,8 @@ int intel_init_vebox_ring_buffer(struct drm_device *dev)
 			GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT;
 	} else {
 		engine->irq_enable_mask = PM_VEBOX_USER_INTERRUPT;
-		engine->irq_get = hsw_vebox_get_irq;
-		engine->irq_put = hsw_vebox_put_irq;
+		engine->irq_enable = hsw_vebox_irq_enable;
+		engine->irq_disable = hsw_vebox_irq_disable;
 	}
 
 	return intel_init_ring_buffer(dev, engine);

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -189,11 +189,10 @@ struct intel_engine_cs {
 	struct intel_hw_status_page status_page;
 	struct i915_ctx_workarounds wa_ctx;
 
-	unsigned irq_refcount; /* protected by dev_priv->irq_lock */
 	bool		irq_posted;
 	u32		irq_enable_mask;	/* bitmask to enable ring interrupt */
-	bool __must_check (*irq_get)(struct intel_engine_cs *ring);
-	void		(*irq_put)(struct intel_engine_cs *ring);
+	void		(*irq_enable)(struct intel_engine_cs *ring);
+	void		(*irq_disable)(struct intel_engine_cs *ring);
 
 	int		(*init_hw)(struct intel_engine_cs *ring);