amdgpu/dc: convert dc_gamma to kref reference counting.

Rolling your own reference counting is frowned upon.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_surface.c

@@ -129,18 +129,18 @@ void dc_plane_state_release(struct dc_plane_state *plane_state)
 
 void dc_gamma_retain(struct dc_gamma *gamma)
 {
-	ASSERT(atomic_read(&gamma->ref_count) > 0);
-	atomic_inc(&gamma->ref_count);
+	kref_get(&gamma->refcount);
 }
 
-void dc_gamma_release(struct dc_gamma **gamma)
+static void dc_gamma_free(struct kref *kref)
 {
-	ASSERT(atomic_read(&(*gamma)->ref_count) > 0);
-	atomic_dec(&(*gamma)->ref_count);
-
-	if (atomic_read(&(*gamma)->ref_count) == 0)
-		kfree((*gamma));
+	struct dc_gamma *gamma = container_of(kref, struct dc_gamma, refcount);
+	kfree(gamma);
+}
 
+void dc_gamma_release(struct dc_gamma **gamma)
+{
+	kref_put(&(*gamma)->refcount, dc_gamma_free);
 	*gamma = NULL;
 }
 
@@ -151,8 +151,7 @@ struct dc_gamma *dc_create_gamma()
 	if (gamma == NULL)
 		goto alloc_fail;
 
-	atomic_inc(&gamma->ref_count);
-
+	kref_init(&gamma->refcount);
 	return gamma;
 
 alloc_fail:

drivers/gpu/drm/amd/display/dc/dc_hw_types.h

@@ -420,6 +420,7 @@ enum dc_gamma_type {
 };
 
 struct dc_gamma {
+	struct kref refcount;
 	enum dc_gamma_type type;
 	unsigned int num_entries;
 
@@ -431,9 +432,6 @@ struct dc_gamma {
 
 	/* private to DC core */
 	struct dc_context *ctx;
-
-	/* private to dc_surface.c */
-	atomic_t ref_count;
 };
 
 /* Used by both ipp amd opp functions*/