drm/i915: use PIPE_CONTROL instruction on Ironlake and Sandy Bridge

Since 965, the hardware has supported the PIPE_CONTROL command, which
provides fine grained GPU cache flushing control.  On recent chipsets,
this instruction is required for reliable interrupt and sequence number
reporting in the driver.

So add support for this instruction, including workarounds, on Ironlake
and Sandy Bridge hardware.

https://bugs.freedesktop.org/show_bug.cgi?id=27108

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 133 insertions, 12 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 8a87717..7f52cc1 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1588,6 +1588,13 @@ i915_gem_process_flushing_list(struct drm_device *dev,
 	}
 }
 
+#define PIPE_CONTROL_FLUSH(addr)					\
+	OUT_RING(GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |		\
+		 PIPE_CONTROL_DEPTH_STALL);				\
+	OUT_RING(addr | PIPE_CONTROL_GLOBAL_GTT);			\
+	OUT_RING(0);							\
+	OUT_RING(0);							\
+
 /**
  * Creates a new sequence number, emitting a write of it to the status page
  * plus an interrupt, which will trigger i915_user_interrupt_handler.
@@ -1622,13 +1629,47 @@ i915_add_request(struct drm_device *dev, struct drm_file *file_priv,
 	if (dev_priv->mm.next_gem_seqno == 0)
 		dev_priv->mm.next_gem_seqno++;
 
-	BEGIN_LP_RING(4);
-	OUT_RING(MI_STORE_DWORD_INDEX);
-	OUT_RING(I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
-	OUT_RING(seqno);
+	if (HAS_PIPE_CONTROL(dev)) {
+		u32 scratch_addr = dev_priv->seqno_gfx_addr + 128;
 
-	OUT_RING(MI_USER_INTERRUPT);
-	ADVANCE_LP_RING();
+		/*
+		 * Workaround qword write incoherence by flushing the
+		 * PIPE_NOTIFY buffers out to memory before requesting
+		 * an interrupt.
+		 */
+		BEGIN_LP_RING(32);
+		OUT_RING(GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |
+			 PIPE_CONTROL_WC_FLUSH | PIPE_CONTROL_TC_FLUSH);
+		OUT_RING(dev_priv->seqno_gfx_addr | PIPE_CONTROL_GLOBAL_GTT);
+		OUT_RING(seqno);
+		OUT_RING(0);
+		PIPE_CONTROL_FLUSH(scratch_addr);
+		scratch_addr += 128; /* write to separate cachelines */
+		PIPE_CONTROL_FLUSH(scratch_addr);
+		scratch_addr += 128;
+		PIPE_CONTROL_FLUSH(scratch_addr);
+		scratch_addr += 128;
+		PIPE_CONTROL_FLUSH(scratch_addr);
+		scratch_addr += 128;
+		PIPE_CONTROL_FLUSH(scratch_addr);
+		scratch_addr += 128;
+		PIPE_CONTROL_FLUSH(scratch_addr);
+		OUT_RING(GFX_OP_PIPE_CONTROL | PIPE_CONTROL_QW_WRITE |
+			 PIPE_CONTROL_WC_FLUSH | PIPE_CONTROL_TC_FLUSH |
+			 PIPE_CONTROL_NOTIFY);
+		OUT_RING(dev_priv->seqno_gfx_addr | PIPE_CONTROL_GLOBAL_GTT);
+		OUT_RING(seqno);
+		OUT_RING(0);
+		ADVANCE_LP_RING();
+	} else {
+		BEGIN_LP_RING(4);
+		OUT_RING(MI_STORE_DWORD_INDEX);
+		OUT_RING(I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
+		OUT_RING(seqno);
+
+		OUT_RING(MI_USER_INTERRUPT);
+		ADVANCE_LP_RING();
+	}
 
 	DRM_DEBUG_DRIVER("%d\n", seqno);
 
@@ -1752,7 +1793,10 @@ i915_get_gem_seqno(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
 
-	return READ_HWSP(dev_priv, I915_GEM_HWS_INDEX);
+	if (IS_I965G(dev))
+		return ((volatile u32 *)(dev_priv->seqno_page))[0];
+	else
+		return READ_HWSP(dev_priv, I915_GEM_HWS_INDEX);
 }
 
 /**
@@ -4552,6 +4596,49 @@ i915_gem_idle(struct drm_device *dev)
 	return 0;
 }
 
+/*
+ * 965+ support PIPE_CONTROL commands, which provide finer grained control
+ * over cache flushing.
+ */
+static int
+i915_gem_init_pipe_control(struct drm_device *dev)
+{
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_gem_object *obj;
+	struct drm_i915_gem_object *obj_priv;
+	int ret;
+
+	obj = drm_gem_object_alloc(dev, 4096);
+	if (obj == NULL) {
+		DRM_ERROR("Failed to allocate seqno page\n");
+		ret = -ENOMEM;
+		goto err;
+	}
+	obj_priv = to_intel_bo(obj);
+	obj_priv->agp_type = AGP_USER_CACHED_MEMORY;
+
+	ret = i915_gem_object_pin(obj, 4096);
+	if (ret)
+		goto err_unref;
+
+	dev_priv->seqno_gfx_addr = obj_priv->gtt_offset;
+	dev_priv->seqno_page =  kmap(obj_priv->pages[0]);
+	if (dev_priv->seqno_page == NULL)
+		goto err_unpin;
+
+	dev_priv->seqno_obj = obj;
+	memset(dev_priv->seqno_page, 0, PAGE_SIZE);
+
+	return 0;
+
+err_unpin:
+	i915_gem_object_unpin(obj);
+err_unref:
+	drm_gem_object_unreference(obj);
+err:
+	return ret;
+}
+
 static int
 i915_gem_init_hws(struct drm_device *dev)
 {
@@ -4569,7 +4656,8 @@ i915_gem_init_hws(struct drm_device *dev)
 	obj = drm_gem_object_alloc(dev, 4096);
 	if (obj == NULL) {
 		DRM_ERROR("Failed to allocate status page\n");
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto err;
 	}
 	obj_priv = to_intel_bo(obj);
 	obj_priv->agp_type = AGP_USER_CACHED_MEMORY;
@@ -4577,7 +4665,7 @@ i915_gem_init_hws(struct drm_device *dev)
 	ret = i915_gem_object_pin(obj, 4096);
 	if (ret != 0) {
 		drm_gem_object_unreference(obj);
-		return ret;
+		goto err_unref;
 	}
 
 	dev_priv->status_gfx_addr = obj_priv->gtt_offset;
@@ -4586,10 +4674,16 @@ i915_gem_init_hws(struct drm_device *dev)
 	if (dev_priv->hw_status_page == NULL) {
 		DRM_ERROR("Failed to map status page.\n");
 		memset(&dev_priv->hws_map, 0, sizeof(dev_priv->hws_map));
-		i915_gem_object_unpin(obj);
-		drm_gem_object_unreference(obj);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto err_unpin;
 	}
+
+	if (HAS_PIPE_CONTROL(dev)) {
+		ret = i915_gem_init_pipe_control(dev);
+		if (ret)
+			goto err_unpin;
+	}
+
 	dev_priv->hws_obj = obj;
 	memset(dev_priv->hw_status_page, 0, PAGE_SIZE);
 	if (IS_GEN6(dev)) {
@@ -4602,6 +4696,30 @@ i915_gem_init_hws(struct drm_device *dev)
 	DRM_DEBUG_DRIVER("hws offset: 0x%08x\n", dev_priv->status_gfx_addr);
 
 	return 0;
+
+err_unpin:
+	i915_gem_object_unpin(obj);
+err_unref:
+	drm_gem_object_unreference(obj);
+err:
+	return 0;
+}
+
+static void
+i915_gem_cleanup_pipe_control(struct drm_device *dev)
+{
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_gem_object *obj;
+	struct drm_i915_gem_object *obj_priv;
+
+	obj = dev_priv->seqno_obj;
+	obj_priv = to_intel_bo(obj);
+	kunmap(obj_priv->pages[0]);
+	i915_gem_object_unpin(obj);
+	drm_gem_object_unreference(obj);
+	dev_priv->seqno_obj = NULL;
+
+	dev_priv->seqno_page = NULL;
 }
 
 static void
@@ -4625,6 +4743,9 @@ i915_gem_cleanup_hws(struct drm_device *dev)
 	memset(&dev_priv->hws_map, 0, sizeof(dev_priv->hws_map));
 	dev_priv->hw_status_page = NULL;
 
+	if (HAS_PIPE_CONTROL(dev))
+		i915_gem_cleanup_pipe_control(dev);
+
 	/* Write high address into HWS_PGA when disabling. */
 	I915_WRITE(HWS_PGA, 0x1ffff000);
 }