drm/radeon: implement unpin function, v2

Changes since v1:
- Fixup compiler warning in unpin function.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_drv.c

@@ -128,6 +128,7 @@ struct drm_gem_object *radeon_gem_prime_import_sg_table(struct drm_device *dev,
 							size_t size,
 							struct sg_table *sg);
 int radeon_gem_prime_pin(struct drm_gem_object *obj);
+void radeon_gem_prime_unpin(struct drm_gem_object *obj);
 void *radeon_gem_prime_vmap(struct drm_gem_object *obj);
 void radeon_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr);
 extern long radeon_kms_compat_ioctl(struct file *filp, unsigned int cmd,
@@ -427,6 +428,7 @@ static struct drm_driver kms_driver = {
 	.gem_prime_export = drm_gem_prime_export,
 	.gem_prime_import = drm_gem_prime_import,
 	.gem_prime_pin = radeon_gem_prime_pin,
+	.gem_prime_unpin = radeon_gem_prime_unpin,
 	.gem_prime_get_sg_table = radeon_gem_prime_get_sg_table,
 	.gem_prime_import_sg_table = radeon_gem_prime_import_sg_table,
 	.gem_prime_vmap = radeon_gem_prime_vmap,

drivers/gpu/drm/radeon/radeon_prime.c

@@ -88,11 +88,19 @@ int radeon_gem_prime_pin(struct drm_gem_object *obj)
 
 	/* pin buffer into GTT */
 	ret = radeon_bo_pin(bo, RADEON_GEM_DOMAIN_GTT, NULL);
-	if (ret) {
 	radeon_bo_unreserve(bo);
 	return ret;
-	}
-	radeon_bo_unreserve(bo);
+}
+
+void radeon_gem_prime_unpin(struct drm_gem_object *obj)
+{
+	struct radeon_bo *bo = gem_to_radeon_bo(obj);
+	int ret = 0;
 
-	return 0;
+	ret = radeon_bo_reserve(bo, false);
+	if (unlikely(ret != 0))
+		return;
+
+	radeon_bo_unpin(bo);
+	radeon_bo_unreserve(bo);
 }