[Intel-gfx] [PATCH v2] drm/i915/vlv: Added a rendering specific Hw WA 'WaSendDummy3dPrimitveAfterSetContext'

[akash.goel at intel.com]

From: Akash Goel <akash.goel at intel.com>

This workaround is needed on VLV for the HW context feature.
It is used after adding the mi_set_context command in ring buffer
for Hw context switch. As per the spec
"The software must send a pipe_control with a CS stall and a post sync
operation and then a dummy DRAW after every MI_SET_CONTEXT and after any
PIPELINE_SELECT that is enabling 3D mode".

v2: Modified the WA comment. (Ville)

Signed-off-by: Akash Goel <akash.goel at intel.com>
---
 drivers/gpu/drm/i915/i915_gem_context.c | 65 ++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_reg.h         |  3 ++
 drivers/gpu/drm/i915/intel_ringbuffer.c |  9 +++++
 drivers/gpu/drm/i915/intel_ringbuffer.h |  1 +
 4 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 19fd362..bc2868d 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -541,6 +541,58 @@ i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id)
 	return ctx;
 }
 
+static inline void
+mi_set_context_dummy3d_prim_wa(struct intel_ring_buffer *ring)
+{
+	u32 scratch_addr;
+	u32 flags = 0;
+
+	/*
+	 * Check if we have the scratch page allocated needed
+	 * for the Pipe Control command, otherwise don't apply
+	 * the dummmy 3d primitive workaround & add NOOPs instead
+	 */
+	if (get_pipe_control_scratch_addr(ring)) {
+		/* Actual scratch location is at 128 bytes offset */
+		scratch_addr = get_pipe_control_scratch_addr(ring) + 128;
+
+		/*
+		 * WaSendDummy3dPrimitveAfterSetContext
+		 * Software must send a pipe_control with a CS stall
+		 * and a post sync operation and then a dummy DRAW after
+		 * every MI_SET_CONTEXT and after any PIPELINE_SELECT that
+		 * is enabling 3D mode. A dummy draw is a 3DPRIMITIVE command
+		 * with Indirect Parameter Enable set to 0, UAV Coherency
+		 * Required set to 0, Predicate Enable set to 0,
+		 * End Offset Enable set to 0, and Vertex Count Per Instance
+		 * set to 0, All other parameters are a don't care.
+		 */
+
+		/*
+		 * Add a pipe control with CS Stall and postsync op
+		 * before dummy 3D_PRIMITIVE
+		 */
+		flags |= PIPE_CONTROL_QW_WRITE | PIPE_CONTROL_CS_STALL;
+		intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
+		intel_ring_emit(ring, flags);
+		intel_ring_emit(ring, scratch_addr | PIPE_CONTROL_GLOBAL_GTT);
+		intel_ring_emit(ring, 0);
+
+		/* Add a dummy 3D_PRIMITVE */
+	intel_ring_emit(ring, GFX_OP_3DPRIMITIVE());
+		intel_ring_emit(ring, 4); /* PrimTopoType*/
+		intel_ring_emit(ring, 0); /* VertexCountPerInstance */
+		intel_ring_emit(ring, 0); /* StartVertexLocation */
+		intel_ring_emit(ring, 0); /* InstanceCount */
+		intel_ring_emit(ring, 0); /* StartInstanceLocation */
+		intel_ring_emit(ring, 0); /* BaseVertexLocation  */
+	} else {
+		int i;
+		for (i = 0; i < 11; i++)
+			intel_ring_emit(ring, MI_NOOP);
+	}
+}
+
 static inline int
 mi_set_context(struct intel_ring_buffer *ring,
 	       struct i915_hw_context *new_context,
@@ -559,7 +611,10 @@ mi_set_context(struct intel_ring_buffer *ring,
 			return ret;
 	}
 
-	ret = intel_ring_begin(ring, 6);
+	if (IS_VALLEYVIEW(ring->dev))
+		ret = intel_ring_begin(ring, 6+4+8);
+	else
+		ret = intel_ring_begin(ring, 6);
 	if (ret)
 		return ret;
 
@@ -583,7 +638,13 @@ mi_set_context(struct intel_ring_buffer *ring,
 	intel_ring_emit(ring, MI_NOOP);
 
 	if (IS_GEN7(ring->dev))
-		intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_ENABLE);
+		if (IS_VALLEYVIEW(ring->dev)) {
+			/* FIXME, should also apply to ivb */
+			mi_set_context_dummy3d_prim_wa(ring);
+			intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_ENABLE);
+			intel_ring_emit(ring, MI_NOOP);
+		} else
+			intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_ENABLE);
 	else
 		intel_ring_emit(ring, MI_NOOP);
 
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index f73a49d..9a1fee6 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -335,6 +335,9 @@
 #define   PIPE_CONTROL_DEPTH_CACHE_FLUSH		(1<<0)
 #define   PIPE_CONTROL_GLOBAL_GTT (1<<2) /* in addr dword */
 
+#define GFX_OP_3DPRIMITIVE()              \
+	((0x3<<29)|(0x3<<27)|(0x3<<24)|       \
+	 (0x0<<16)|(0x0<<10)|(0x0<<8)|(7-2))
 
 /*
  * Reset registers
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 0d7d927b..812039a 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -556,6 +556,15 @@ err:
 	return ret;
 }
 
+u32
+get_pipe_control_scratch_addr(struct intel_ring_buffer *ring)
+{
+	if (ring->scratch.obj == NULL)
+		return 0;
+
+	return ring->scratch.gtt_offset;
+}
+
 static int init_render_ring(struct intel_ring_buffer *ring)
 {
 	struct drm_device *dev = ring->dev;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 38c757e..6c52d59 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -259,6 +259,7 @@ int intel_init_vebox_ring_buffer(struct drm_device *dev);
 
 u32 intel_ring_get_active_head(struct intel_ring_buffer *ring);
 void intel_ring_setup_status_page(struct intel_ring_buffer *ring);
+u32 get_pipe_control_scratch_addr(struct intel_ring_buffer *ring);
 
 static inline u32 intel_ring_get_tail(struct intel_ring_buffer *ring)
 {
-- 
1.8.5.2