[Intel-gfx] [PATCH 40/50] drm/i915/bdw: Handle context switch events

oscar.mateo at intel.com oscar.mateo at intel.com
Fri May 9 14:09:10 CEST 2014


From: Thomas Daniel <thomas.daniel at intel.com>

Handle all context status events in the context status buffer on every
context switch interrupt. We only remove work from the execlist queue
after a context status buffer reports that it has completed and we only
attempt to schedule new contexts on interrupt when a previously submitted
context completes (unless no contexts are queued, which means the GPU is
free).

Signed-off-by: Thomas Daniel <thomas.daniel at intel.com>

v2: Unreferencing the context when we are freeing the request might free
the backing bo, which requires the struct_mutex to be grabbed, so defer
unreferencing and freeing to a bottom half.

v3:
- Ack the interrupt inmediately, before trying to handle it (fix for
missing interrupts by Bob Beckett <robert.beckett at intel.com>).
- Update the Context Status Buffer Read Pointer, just in case (spotted
by Damien Lespiau).

Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h         |   3 +
 drivers/gpu/drm/i915/i915_irq.c         |  38 +++++++-----
 drivers/gpu/drm/i915/intel_lrc.c        | 102 +++++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/intel_ringbuffer.c |   1 +
 drivers/gpu/drm/i915/intel_ringbuffer.h |   1 +
 5 files changed, 129 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index f2aae6a..07b8bdc 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1748,6 +1748,8 @@ struct drm_i915_gem_request {
 
 	/** execlist queue entry for this request */
 	struct list_head execlist_link;
+	/** Struct to handle this request in the bottom half of an interrupt */
+	struct work_struct work;
 };
 
 struct drm_i915_file_private {
@@ -2449,6 +2451,7 @@ static inline u32 intel_get_lr_contextid(struct drm_i915_gem_object *ctx_obj)
 int gen8_switch_context_queue(struct intel_engine *ring,
 			      struct i915_hw_context *to,
 			      u32 tail);
+void gen8_handle_context_events(struct intel_engine *ring);
 
 /* i915_gem_evict.c */
 int __must_check i915_gem_evict_something(struct drm_device *dev,
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index a28cf6c..fbffead 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1300,6 +1300,7 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
 				       struct drm_i915_private *dev_priv,
 				       u32 master_ctl)
 {
+	struct intel_engine *ring;
 	u32 rcs, bcs, vcs, vecs;
 	uint32_t tmp = 0;
 	irqreturn_t ret = IRQ_NONE;
@@ -1307,16 +1308,22 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
 	if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
 		tmp = I915_READ(GEN8_GT_IIR(0));
 		if (tmp) {
+			I915_WRITE(GEN8_GT_IIR(0), tmp);
 			ret = IRQ_HANDLED;
+
 			rcs = tmp >> GEN8_RCS_IRQ_SHIFT;
-			bcs = tmp >> GEN8_BCS_IRQ_SHIFT;
+			ring = &dev_priv->ring[RCS];
 			if (rcs & GT_RENDER_USER_INTERRUPT)
-				notify_ring(dev, &dev_priv->ring[RCS]);
+				notify_ring(dev, ring);
+			if (rcs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
+				gen8_handle_context_events(ring);
+
+			bcs = tmp >> GEN8_BCS_IRQ_SHIFT;
+			ring = &dev_priv->ring[BCS];
 			if (bcs & GT_RENDER_USER_INTERRUPT)
-				notify_ring(dev, &dev_priv->ring[BCS]);
-			if ((rcs | bcs) & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
-			     DRM_DEBUG_DRIVER("TODO: Context switch\n");
-			I915_WRITE(GEN8_GT_IIR(0), tmp);
+				notify_ring(dev, ring);
+			if (bcs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
+				gen8_handle_context_events(ring);
 		} else
 			DRM_ERROR("The master control interrupt lied (GT0)!\n");
 	}
@@ -1324,18 +1331,20 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
 	if (master_ctl & (GEN8_GT_VCS1_IRQ | GEN8_GT_VCS2_IRQ)) {
 		tmp = I915_READ(GEN8_GT_IIR(1));
 		if (tmp) {
+			I915_WRITE(GEN8_GT_IIR(1), tmp);
 			ret = IRQ_HANDLED;
 			vcs = tmp >> GEN8_VCS1_IRQ_SHIFT;
+			ring = &dev_priv->ring[VCS];
 			if (vcs & GT_RENDER_USER_INTERRUPT)
-				notify_ring(dev, &dev_priv->ring[VCS]);
+				notify_ring(dev, ring);
 			if (vcs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
-			     DRM_DEBUG_DRIVER("TODO: Context switch\n");
+			     gen8_handle_context_events(ring);
 			vcs = tmp >> GEN8_VCS2_IRQ_SHIFT;
+			ring = &dev_priv->ring[VCS2];
 			if (vcs & GT_RENDER_USER_INTERRUPT)
-				notify_ring(dev, &dev_priv->ring[VCS2]);
+				notify_ring(dev, ring);
 			if (vcs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
-			     DRM_DEBUG_DRIVER("TODO: Context switch\n");
-			I915_WRITE(GEN8_GT_IIR(1), tmp);
+			     gen8_handle_context_events(ring);
 		} else
 			DRM_ERROR("The master control interrupt lied (GT1)!\n");
 	}
@@ -1343,13 +1352,14 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
 	if (master_ctl & GEN8_GT_VECS_IRQ) {
 		tmp = I915_READ(GEN8_GT_IIR(3));
 		if (tmp) {
+			I915_WRITE(GEN8_GT_IIR(3), tmp);
 			ret = IRQ_HANDLED;
 			vecs = tmp >> GEN8_VECS_IRQ_SHIFT;
+			ring = &dev_priv->ring[VECS];
 			if (vecs & GT_RENDER_USER_INTERRUPT)
-				notify_ring(dev, &dev_priv->ring[VECS]);
+				notify_ring(dev, ring);
 			if (vecs & GEN8_GT_CONTEXT_SWITCH_INTERRUPT)
-			     DRM_DEBUG_DRIVER("TODO: Context switch\n");
-			I915_WRITE(GEN8_GT_IIR(3), tmp);
+				gen8_handle_context_events(ring);
 		} else
 			DRM_ERROR("The master control interrupt lied (GT3)!\n");
 	}
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 6da7db9..1ff493a 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -49,6 +49,22 @@
 #define RING_ELSP(ring)			((ring)->mmio_base+0x230)
 #define RING_EXECLIST_STATUS(ring)	((ring)->mmio_base+0x234)
 #define RING_CONTEXT_CONTROL(ring)	((ring)->mmio_base+0x244)
+#define RING_CONTEXT_STATUS_BUF(ring)	((ring)->mmio_base+0x370)
+#define RING_CONTEXT_STATUS_PTR(ring)	((ring)->mmio_base+0x3a0)
+
+#define RING_EXECLIST_QFULL		(1 << 0x2)
+#define RING_EXECLIST1_VALID		(1 << 0x3)
+#define RING_EXECLIST0_VALID		(1 << 0x4)
+#define RING_EXECLIST_ACTIVE_STATUS	(3 << 0xE)
+#define RING_EXECLIST1_ACTIVE		(1 << 0x11)
+#define RING_EXECLIST0_ACTIVE		(1 << 0x12)
+
+#define GEN8_CTX_STATUS_IDLE_ACTIVE	(1 << 0)
+#define GEN8_CTX_STATUS_PREEMPTED	(1 << 1)
+#define GEN8_CTX_STATUS_ELEMENT_SWITCH	(1 << 2)
+#define GEN8_CTX_STATUS_ACTIVE_IDLE	(1 << 3)
+#define GEN8_CTX_STATUS_COMPLETE	(1 << 4)
+#define GEN8_CTX_STATUS_LITE_RESTORE	(1 << 15)
 
 #define CTX_LRI_HEADER_0		0x01
 #define CTX_CONTEXT_CONTROL		0x02
@@ -203,6 +219,9 @@ static void gen8_switch_context_unqueue(struct intel_engine *ring)
 {
 	struct drm_i915_gem_request *req0 = NULL, *req1 = NULL;
 	struct drm_i915_gem_request *cursor = NULL, *tmp = NULL;
+	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+
+	assert_spin_locked(&ring->execlist_lock);
 
 	if (list_empty(&ring->execlist_queue))
 		return;
@@ -215,8 +234,7 @@ static void gen8_switch_context_unqueue(struct intel_engine *ring)
 			/* Same ctx: ignore first request, as second request
 			 * will update tail past first request's workload */
 			list_del(&req0->execlist_link);
-			i915_gem_context_unreference(req0->ctx);
-			kfree(req0);
+			queue_work(dev_priv->wq, &req0->work);
 			req0 = cursor;
 		} else {
 			req1 = cursor;
@@ -228,6 +246,85 @@ static void gen8_switch_context_unqueue(struct intel_engine *ring)
 			req1? req1->ctx : NULL, req1? req1->tail : 0));
 }
 
+static bool check_remove_request(struct intel_engine *ring, u32 request_id)
+{
+	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+	struct drm_i915_gem_request *head_req;
+
+	assert_spin_locked(&ring->execlist_lock);
+
+	head_req = list_first_entry_or_null(&ring->execlist_queue,
+			struct drm_i915_gem_request, execlist_link);
+	if (head_req != NULL) {
+		struct drm_i915_gem_object *ctx_obj =
+				head_req->ctx->engine[ring->id].obj;
+		if (intel_get_lr_contextid(ctx_obj) == request_id) {
+			list_del(&head_req->execlist_link);
+			queue_work(dev_priv->wq, &head_req->work);
+			return true;
+		}
+	}
+
+	return false;
+}
+
+void gen8_handle_context_events(struct intel_engine *ring)
+{
+	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+	u32 status_pointer;
+	u8 read_pointer;
+	u8 write_pointer;
+	u32 status;
+	u32 status_id;
+	u32 submit_contexts = 0;
+
+	status_pointer = I915_READ(RING_CONTEXT_STATUS_PTR(ring));
+
+	read_pointer = ring->next_context_status_buffer;
+	write_pointer = status_pointer & 0x07;
+	if (read_pointer > write_pointer)
+		write_pointer += 6;
+
+	spin_lock(&ring->execlist_lock);
+
+	while (read_pointer < write_pointer) {
+		read_pointer++;
+		status = I915_READ(RING_CONTEXT_STATUS_BUF(ring) +
+				(read_pointer % 6) * 8);
+		status_id = I915_READ(RING_CONTEXT_STATUS_BUF(ring) +
+				(read_pointer % 6) * 8 + 4);
+
+		if (status & GEN8_CTX_STATUS_COMPLETE) {
+			if (check_remove_request(ring, status_id))
+				submit_contexts++;
+		}
+	}
+
+	if (submit_contexts != 0)
+		gen8_switch_context_unqueue(ring);
+
+	spin_unlock(&ring->execlist_lock);
+
+	WARN(submit_contexts > 2, "More than two context complete events?\n");
+	ring->next_context_status_buffer = write_pointer % 6;
+
+	I915_WRITE(RING_CONTEXT_STATUS_PTR(ring),
+			((u32)ring->next_context_status_buffer & 0x07) << 8);
+}
+
+static void free_request_task(struct work_struct *work)
+{
+	struct drm_i915_gem_request *req =
+			container_of(work, struct drm_i915_gem_request, work);
+	struct drm_device *dev = req->ring->dev;
+
+	mutex_lock(&dev->struct_mutex);
+	i915_gem_context_unreference(req->ctx);
+	mutex_unlock(&dev->struct_mutex);
+
+	kfree(req);
+}
+
 int gen8_switch_context_queue(struct intel_engine *ring,
 			      struct i915_hw_context *to,
 			      u32 tail)
@@ -243,6 +340,7 @@ int gen8_switch_context_queue(struct intel_engine *ring,
 	req->ctx = to;
 	i915_gem_context_reference(req->ctx);
 	req->tail = tail;
+	INIT_WORK(&req->work, free_request_task);
 
 	spin_lock_irqsave(&ring->execlist_lock, flags);
 
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 35ced7c..9cd6ee8 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1573,6 +1573,7 @@ static int intel_init_ring(struct drm_device *dev,
 		if (ring->status_page.page_addr == NULL)
 			return -ENOMEM;
 		ring->status_page.obj = obj;
+		ring->next_context_status_buffer = 0;
 	} else if (I915_NEED_GFX_HWS(dev)) {
 		ret = init_status_page(ring);
 		if (ret)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index daf91de..f3ae547 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -178,6 +178,7 @@ struct intel_engine {
 
 	spinlock_t execlist_lock;
 	struct list_head execlist_queue;
+	u8 next_context_status_buffer;
 
 	struct i915_hw_context *default_context;
 	struct i915_hw_context *last_context;
-- 
1.9.0




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