From: Akash Goel <akash.g...@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".

Signed-off-by: Akash Goel <akash.g...@intel.com>
Signed-off-by: Sourab Gupta <sourab.gu...@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 6043062..544fc2d 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -584,6 +584,58 @@ 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: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  */
+       } 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,
@@ -602,7 +654,10 @@ 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;
 
@@ -626,7 +681,13 @@ 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 adcb9c7..fd25e8e4 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -348,6 +348,9 @@
 #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 2812384..98ddfec 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -560,6 +560,15 @@ 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 f11ceb2..640c56d 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -294,6 +294,7 @@ 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)
 {
-- 
1.8.5.1

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