[Intel-gfx] [PATCH v5 2/6] drm/i915/vlv: Added a rendering specific Hw WA 'WaSendDummy3dPrimitveAfterSetContext'

[sourab.gupta 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".
Tested only for vlv.

v2: Modified the WA comment. (Ville)

v3: Added the vlv identifier with the WA name

v4: Check removed for scratch page initialization. (Chris/Daniel)

v5: Refactored based on latest codebase. Also WA added for full Gen7.

Signed-off-by: Sourab Gupta <sourab.gupta at intel.com>
Signed-off-by: Akash Goel <akash.goel at intel.com>
---
 drivers/gpu/drm/i915/i915_gem_context.c | 55 +++++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_reg.h         |  1 +
 drivers/gpu/drm/i915/intel_ringbuffer.c |  9 ++++++
 drivers/gpu/drm/i915/intel_ringbuffer.h |  1 +
 4 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index f77b4c1..b6d2a67 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -545,6 +545,47 @@ 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;
+
+	/* Actual scratch location is at 128 bytes offset */
+	scratch_addr = intel_get_pipe_control_scratch_addr(ring) + 128;
+
+	/*
+	 * WaSendDummy3dPrimitveAfterSetContext:ivb,vlv
+	 * 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  */
+}
+
 static inline int
 mi_set_context(struct intel_ring_buffer *ring,
 	       struct i915_hw_context *new_context,
@@ -563,7 +604,10 @@ mi_set_context(struct intel_ring_buffer *ring,
 			return ret;
 	}
 
-	ret = intel_ring_begin(ring, 6);
+	if (INTEL_INFO(ring->dev)->gen == 7)
+		ret = intel_ring_begin(ring, 6+4+8);
+	else
+		ret = intel_ring_begin(ring, 6);
 	if (ret)
 		return ret;
 
@@ -586,8 +630,15 @@ mi_set_context(struct intel_ring_buffer *ring,
 	 */
 	intel_ring_emit(ring, MI_NOOP);
 
+	/* WaSendDummy3dPrimitveAfterSetContext:ivb,vlv */
 	if (INTEL_INFO(ring->dev)->gen >= 7)
-		intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_ENABLE);
+		if (INTEL_INFO(ring->dev)->gen == 7) {
+			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 8f84555..1128527 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -355,6 +355,7 @@
 #define   PIPE_CONTROL_STALL_AT_SCOREBOARD		(1<<1)
 #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)|(7-2))
 
 /*
  * Commands used only by the command parser
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index eb3dd26..834411b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -585,6 +585,15 @@ err:
 	return ret;
 }
 
+u32
+intel_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 413cdc7..ffaed8b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -291,6 +291,7 @@ int intel_init_vebox_ring_buffer(struct drm_device *dev);
 
 u64 intel_ring_get_active_head(struct intel_ring_buffer *ring);
 void intel_ring_setup_status_page(struct intel_ring_buffer *ring);
+u32 intel_get_pipe_control_scratch_addr(struct intel_ring_buffer *ring);
 
 static inline u32 intel_ring_get_tail(struct intel_ring_buffer *ring)
 {
-- 
1.8.5.1