Re: [PATCH v7 4/7] drm: writeback: Create an helper for drm_writeback_connector initialization

[kernel test robot <lkp@intel.com>]

Hi Louis,

kernel test robot noticed the following build warnings:

[auto build test WARNING on f8a2397baf041a5cee408b082334bb09c7e161df]

url:    https://github.com/intel-lab-lkp/linux/commits/Louis-Chauvet/drm-vkms-Switch-to-managed-for-connector/20250114-011112
base:   f8a2397baf041a5cee408b082334bb09c7e161df
patch link:    https://lore.kernel.org/r/20250113-google-vkms-managed-v7-4-4f81d1893e0b%40bootlin.com
patch subject: [PATCH v7 4/7] drm: writeback: Create an helper for drm_writeback_connector initialization
config: i386-randconfig-014-20250115 (https://download.01.org/0day-ci/archive/20250115/202501150938.a3MspUwj-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250115/202501150938.a3MspUwj-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202501150938.a3MspUwj-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/drm_writeback.c: In function 'drm_writeback_connector_init_with_encoder':
>> drivers/gpu/drm/drm_writeback.c:321:35: warning: unused variable 'blob' [-Wunused-variable]
     321 |         struct drm_property_blob *blob;
         |                                   ^~~~
   drivers/gpu/drm/drm_writeback.c: At top level:
   drivers/gpu/drm/drm_writeback.c:348:13: warning: 'drm_writeback_connector_cleanup' defined but not used [-Wunused-function]
     348 | static void drm_writeback_connector_cleanup(struct drm_device *dev,
         |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
>> drivers/gpu/drm/drm_writeback.c:243: warning: expecting prototype for drm_writeback_connector_init_with_encoder(). Prototype was for __drm_writeback_connector_init() instead


vim +/blob +321 drivers/gpu/drm/drm_writeback.c

   214	
   215	/**
   216	 * drm_writeback_connector_init_with_encoder - Initialize a writeback connector with
   217	 * a custom encoder
   218	 *
   219	 * @dev: DRM device
   220	 * @wb_connector: Writeback connector to initialize
   221	 * @enc: handle to the already initialized drm encoder
   222	 * @formats: Array of supported pixel formats for the writeback engine
   223	 * @n_formats: Length of the formats array
   224	 *
   225	 * This function creates the writeback-connector-specific properties if they
   226	 * have not been already created, initializes the connector as
   227	 * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
   228	 * values.
   229	 *
   230	 * This function assumes that the drm_writeback_connector's encoder has already been
   231	 * created and initialized before invoking this function.
   232	 *
   233	 * In addition, this function also assumes that callers of this API will manage
   234	 * assigning the encoder helper functions, possible_crtcs and any other encoder
   235	 * specific operation.
   236	 *
   237	 * Returns: 0 on success, or a negative error code
   238	 */
   239	static int __drm_writeback_connector_init(struct drm_device *dev,
   240						  struct drm_writeback_connector *wb_connector,
   241						  struct drm_encoder *enc, const u32 *formats,
   242						  int n_formats)
 > 243	{
   244		struct drm_connector *connector = &wb_connector->base;
   245		struct drm_mode_config *config = &dev->mode_config;
   246		struct drm_property_blob *blob;
   247		int ret = create_writeback_properties(dev);
   248	
   249		if (ret != 0)
   250			return ret;
   251	
   252		connector->interlace_allowed = 0;
   253	
   254		ret = drm_connector_attach_encoder(connector, enc);
   255		if (ret)
   256			return ret;
   257	
   258		blob = drm_property_create_blob(dev, n_formats * sizeof(*formats),
   259						formats);
   260		if (IS_ERR(blob))
   261			return PTR_ERR(blob);
   262	
   263		INIT_LIST_HEAD(&wb_connector->job_queue);
   264		spin_lock_init(&wb_connector->job_lock);
   265	
   266		wb_connector->fence_context = dma_fence_context_alloc(1);
   267		spin_lock_init(&wb_connector->fence_lock);
   268		snprintf(wb_connector->timeline_name,
   269			 sizeof(wb_connector->timeline_name),
   270			 "CONNECTOR:%d-%s", connector->base.id, connector->name);
   271	
   272		drm_object_attach_property(&connector->base,
   273					   config->writeback_out_fence_ptr_property, 0);
   274	
   275		drm_object_attach_property(&connector->base,
   276					   config->writeback_fb_id_property, 0);
   277	
   278		drm_object_attach_property(&connector->base,
   279					   config->writeback_pixel_formats_property,
   280					   blob->base.id);
   281		wb_connector->pixel_formats_blob_ptr = blob;
   282	
   283		return 0;
   284	}
   285	
   286	/**
   287	 * drm_writeback_connector_init_with_encoder - Initialize a writeback connector with
   288	 * a custom encoder
   289	 *
   290	 * @dev: DRM device
   291	 * @wb_connector: Writeback connector to initialize
   292	 * @enc: handle to the already initialized drm encoder
   293	 * @con_funcs: Connector funcs vtable
   294	 * @formats: Array of supported pixel formats for the writeback engine
   295	 * @n_formats: Length of the formats array
   296	 *
   297	 * This function creates the writeback-connector-specific properties if they
   298	 * have not been already created, initializes the connector as
   299	 * type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
   300	 * values.
   301	 *
   302	 * This function assumes that the drm_writeback_connector's encoder has already been
   303	 * created and initialized before invoking this function.
   304	 *
   305	 * In addition, this function also assumes that callers of this API will manage
   306	 * assigning the encoder helper functions, possible_crtcs and any other encoder
   307	 * specific operation.
   308	 *
   309	 * Drivers should always use this function instead of drm_connector_init() to
   310	 * set up writeback connectors if they want to manage themselves the lifetime of the
   311	 * associated encoder.
   312	 *
   313	 * Returns: 0 on success, or a negative error code
   314	 */
   315	int drm_writeback_connector_init_with_encoder(struct drm_device *dev,
   316						      struct drm_writeback_connector *wb_connector,
   317						      struct drm_encoder *enc,
   318						      const struct drm_connector_funcs *con_funcs,
   319						      const u32 *formats, int n_formats)
   320	{
 > 321		struct drm_property_blob *blob;
   322		struct drm_connector *connector = &wb_connector->base;
   323		int ret;
   324	
   325		ret = drm_connector_init(dev, connector, con_funcs,
   326					 DRM_MODE_CONNECTOR_WRITEBACK);
   327		if (ret)
   328			return ret;
   329	
   330		ret = __drm_writeback_connector_init(dev, wb_connector, enc, formats,
   331						     n_formats);
   332		if (ret)
   333			drm_connector_cleanup(connector);
   334	
   335		return ret;
   336	}
   337	EXPORT_SYMBOL(drm_writeback_connector_init_with_encoder);
   338	

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