drm/i915: Remove unnecessary ggtt_offset_bias from i915_gem_context

Since ggtt_offset_bias is now stored in ggtt.pin_bias, it is duplicated
inside i915_gem_context, and can instead be accessed directly from ggtt.

v3:
Added a helper function to retrieve the ggtt.pin_bias from the vma.

v4:
Moved the helper function to the previous patch in the series.
Dropped the bias from intel_ring_pin. This introduces a slight functional
change since we are always pinning the ring a bit higher if GuC is present
even though we don't really need to.

v8:
Fixed patch not applying on the most recent upstream.
Signed-off-by: Jakub Bartmiński <jakub.bartminski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180727141148.30874-4-jakub.bartminski@intel.com

drivers/gpu/drm/i915/i915_gem_context.c

@@ -329,8 +329,6 @@ __create_hw_context(struct drm_i915_private *dev_priv,
 	ctx->desc_template =
 		default_desc_template(dev_priv, dev_priv->mm.aliasing_ppgtt);
 
-	ctx->ggtt_offset_bias = dev_priv->ggtt.pin_bias;
-
 	return ctx;
 
 err_pid:

drivers/gpu/drm/i915/i915_gem_context.h

@@ -147,9 +147,6 @@ struct i915_gem_context {
 
 	struct i915_sched_attr sched;
 
-	/** ggtt_offset_bias: placement restriction for context objects */
-	u32 ggtt_offset_bias;
-
 	/** engine: per-engine logical HW state */
 	struct intel_context {
 		struct i915_gem_context *gem_context;

drivers/gpu/drm/i915/intel_lrc.c

@@ -1303,8 +1303,7 @@ static int __context_pin(struct i915_gem_context *ctx, struct i915_vma *vma)
 	}
 
 	flags = PIN_GLOBAL | PIN_HIGH;
-	if (ctx->ggtt_offset_bias)
-		flags |= PIN_OFFSET_BIAS | ctx->ggtt_offset_bias;
+	flags |= PIN_OFFSET_BIAS | i915_ggtt_pin_bias(vma);
 
 	return i915_vma_pin(vma, 0, 0, flags);
 }
@@ -1332,7 +1331,7 @@ __execlists_context_pin(struct intel_engine_cs *engine,
 		goto unpin_vma;
 	}
 
-	ret = intel_ring_pin(ce->ring, ctx->i915, ctx->ggtt_offset_bias);
+	ret = intel_ring_pin(ce->ring, ctx->i915);
 	if (ret)
 		goto unpin_map;
 

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1003,11 +1003,7 @@ i915_emit_bb_start(struct i915_request *rq,
 	return 0;
 }
 
-
-
-int intel_ring_pin(struct intel_ring *ring,
-		   struct drm_i915_private *i915,
-		   unsigned int offset_bias)
+int intel_ring_pin(struct intel_ring *ring, struct drm_i915_private *i915)
 {
 	enum i915_map_type map = HAS_LLC(i915) ? I915_MAP_WB : I915_MAP_WC;
 	struct i915_vma *vma = ring->vma;
@@ -1017,10 +1013,11 @@ int intel_ring_pin(struct intel_ring *ring,
 
 	GEM_BUG_ON(ring->vaddr);
 
-
 	flags = PIN_GLOBAL;
-	if (offset_bias)
-		flags |= PIN_OFFSET_BIAS | offset_bias;
+
+	/* Ring wraparound at offset 0 sometimes hangs. No idea why. */
+	flags |= PIN_OFFSET_BIAS | i915_ggtt_pin_bias(vma);
+
 	if (vma->obj->stolen)
 		flags |= PIN_MAPPABLE;
 	else
@@ -1408,8 +1405,7 @@ static int intel_init_ring_buffer(struct intel_engine_cs *engine)
 		goto err;
 	}
 
-	/* Ring wraparound at offset 0 sometimes hangs. No idea why. */
-	err = intel_ring_pin(ring, engine->i915, I915_GTT_PAGE_SIZE);
+	err = intel_ring_pin(ring, engine->i915);
 	if (err)
 		goto err_ring;
 

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -797,9 +797,7 @@ struct intel_ring *
 intel_engine_create_ring(struct intel_engine_cs *engine,
 			 struct i915_timeline *timeline,
 			 int size);
-int intel_ring_pin(struct intel_ring *ring,
-		   struct drm_i915_private *i915,
-		   unsigned int offset_bias);
+int intel_ring_pin(struct intel_ring *ring, struct drm_i915_private *i915);
 void intel_ring_reset(struct intel_ring *ring, u32 tail);
 unsigned int intel_ring_update_space(struct intel_ring *ring);
 void intel_ring_unpin(struct intel_ring *ring);