[xilinx-xlnx:master 586/587] drivers/gpu/drm/xlnx/xlnx_mixer.c:2216:9: warning: 'strncpy' specified bound 4 equals destination size

[kernel test robot]

tree:   https://github.com/Xilinx/linux-xlnx master
head:   d152c7d3b7f02c4517cd20098140cfe4ac61179e
commit: 51922bbe4bd943daf9b5684f7deb87ffe82c00a2 [586/587] drm: xlnx: mixer: Correct the fourcc string copy
config: sparc-allyesconfig (https://download.01.org/0day-ci/archive/20220622/202206220204.ZdQS6kJi-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/Xilinx/linux-xlnx/commit/51922bbe4bd943daf9b5684f7deb87ffe82c00a2
        git remote add xilinx-xlnx https://github.com/Xilinx/linux-xlnx
        git fetch --no-tags xilinx-xlnx master
        git checkout 51922bbe4bd943daf9b5684f7deb87ffe82c00a2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=sparc SHELL=/bin/bash drivers/gpu/drm/xlnx/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp at intel.com>

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/xlnx/xlnx_mixer.c: In function 'xlnx_mix_parse_dt_bg_video_fmt':
>> drivers/gpu/drm/xlnx/xlnx_mixer.c:2216:9: warning: 'strncpy' specified bound 4 equals destination size [-Wstringop-truncation]
    2216 |         strncpy((char *)&layer->hw_config.vid_fmt, vformat, 4);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/xlnx/xlnx_mixer.c: In function 'xlnx_mix_of_init_layer':
   drivers/gpu/drm/xlnx/xlnx_mixer.c:2493:9: warning: 'strncpy' specified bound 4 equals destination size [-Wstringop-truncation]
    2493 |         strncpy((char *)&layer->hw_config.vid_fmt, vformat, 4);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/strncpy +2216 drivers/gpu/drm/xlnx/xlnx_mixer.c

  2194	
  2195	static int xlnx_mix_parse_dt_bg_video_fmt(struct device_node *node,
  2196						  struct xlnx_mix_hw *mixer_hw)
  2197	{
  2198		struct device_node *layer_node;
  2199		struct xlnx_mix_layer_data *layer;
  2200		const char *vformat;
  2201	
  2202		layer_node = of_get_child_by_name(node, "layer_0");
  2203		layer = &mixer_hw->layer_data[XVMIX_MASTER_LAYER_IDX];
  2204	
  2205		/* Set default values */
  2206		layer->hw_config.can_alpha = false;
  2207		layer->hw_config.can_scale = false;
  2208		layer->hw_config.min_width = XVMIX_LAYER_WIDTH_MIN;
  2209		layer->hw_config.min_height = XVMIX_LAYER_HEIGHT_MIN;
  2210	
  2211		if (of_property_read_string(layer_node, "xlnx,vformat",
  2212					    &vformat)) {
  2213			DRM_ERROR("No xlnx,vformat value for layer 0 in dts\n");
  2214			return -EINVAL;
  2215		}
> 2216		strncpy((char *)&layer->hw_config.vid_fmt, vformat, 4);
  2217		layer->hw_config.is_streaming =
  2218			of_property_read_bool(layer_node, "xlnx,layer-streaming");
  2219		if (of_property_read_u32(node, "xlnx,bpc", &mixer_hw->bg_layer_bpc)) {
  2220			DRM_ERROR("Failed to get bits per component (bpc) prop\n");
  2221			return -EINVAL;
  2222		}
  2223		if (of_property_read_u32(layer_node, "xlnx,layer-max-width",
  2224					 &layer->hw_config.max_width)) {
  2225			DRM_ERROR("Failed to get screen width prop\n");
  2226			return -EINVAL;
  2227		} else if (layer->hw_config.max_width > XVMIX_DISP_MAX_WIDTH ||
  2228			   layer->hw_config.max_width < XVMIX_DISP_MIN_WIDTH) {
  2229			DRM_ERROR("Invalid width in dt");
  2230			return -EINVAL;
  2231		}
  2232	
  2233		mixer_hw->max_layer_width = layer->hw_config.max_width;
  2234		if (of_property_read_u32(layer_node, "xlnx,layer-max-height",
  2235					 &layer->hw_config.max_height)) {
  2236			DRM_ERROR("Failed to get screen height prop\n");
  2237			return -EINVAL;
  2238		} else if (layer->hw_config.max_height > XVMIX_DISP_MAX_HEIGHT ||
  2239			   layer->hw_config.max_height < XVMIX_DISP_MIN_HEIGHT) {
  2240			DRM_ERROR("Invalid height in dt");
  2241			return -EINVAL;
  2242		}
  2243	
  2244		mixer_hw->max_layer_height = layer->hw_config.max_height;
  2245		layer->id = XVMIX_LAYER_MASTER;
  2246	
  2247		return 0;
  2248	}
  2249	

-- 
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https://01.org/lkp