[PATCH 36/50] drm/i915/bdw: Write the tail pointer, LRC style

[oscar.mateo@intel.com]

From: Oscar Mateo <oscar.mateo@intel.com>

Each logical ring context has the tail pointer in the context object,
so update it before submission.

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 54cbb4b..b06098e 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -158,6 +158,21 @@ static void submit_execlist(struct intel_engine *ring,
 	gen6_gt_force_wake_put(dev_priv, FORCEWAKE_ALL);
 }
 
+static int lr_context_write_tail(struct drm_i915_gem_object *ctx_obj, u32 tail)
+{
+	struct page *page;
+	uint32_t *reg_state;
+
+	page = i915_gem_object_get_page(ctx_obj, 1);
+	reg_state = kmap_atomic(page);
+
+	reg_state[CTX_RING_TAIL+1] = tail;
+
+	kunmap_atomic(reg_state);
+
+	return 0;
+}
+
 static int gen8_switch_context(struct intel_engine *ring,
 		struct i915_hw_context *to0, u32 tail0,
 		struct i915_hw_context *to1, u32 tail1)
@@ -169,10 +184,14 @@ static int gen8_switch_context(struct intel_engine *ring,
 	BUG_ON(!ctx_obj0);
 	BUG_ON(!i915_gem_obj_is_pinned(ctx_obj0));
 
+	lr_context_write_tail(ctx_obj0, tail0);
+
 	if (to1) {
 		ctx_obj1 = to1->engine[ring->id].obj;
 		BUG_ON(!ctx_obj1);
 		BUG_ON(!i915_gem_obj_is_pinned(ctx_obj1));
+
+		lr_context_write_tail(ctx_obj1, tail1);
 	}
 
 	submit_execlist(ring, ctx_obj0, ctx_obj1);
-- 
1.9.0