drm/i915: Extract tile_row_size for fencing

Computing the tile row size of a tiled object (for use with fence
registers) is repeated, so extract it to a common helper.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170109161613.11881-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/i915_gem_object.h b/drivers/gpu/drm/i915/i915_gem_object.h
index 6a368de..ed3f4d5 100644
--- a/drivers/gpu/drm/i915/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/i915_gem_object.h
@@ -317,6 +317,26 @@ i915_gem_object_get_stride(struct drm_i915_gem_object *obj)
 	return obj->tiling_and_stride & STRIDE_MASK;
 }
 
+static inline unsigned int
+i915_gem_tile_height(unsigned int tiling)
+{
+	GEM_BUG_ON(!tiling);
+	return tiling == I915_TILING_Y ? 32 : 8;
+}
+
+static inline unsigned int
+i915_gem_object_get_tile_height(struct drm_i915_gem_object *obj)
+{
+	return i915_gem_tile_height(i915_gem_object_get_tiling(obj));
+}
+
+static inline unsigned int
+i915_gem_object_get_tile_row_size(struct drm_i915_gem_object *obj)
+{
+	return (i915_gem_object_get_stride(obj) *
+		i915_gem_object_get_tile_height(obj));
+}
+
 static inline struct intel_engine_cs *
 i915_gem_object_last_write_engine(struct drm_i915_gem_object *obj)
 {