drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c:532:62-63: WARNING comparing pointer to 0

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   c7402612e2e61b76177f22e6e7f705adcbecc6fe
commit: 5911d02cac70d7fb52009fbd37423e63f8f6f9bc drm/amd/display: Change the DMCUB mailbox memory location from FB to inbox
date:   4 weeks ago
config: x86_64-randconfig-104-20231214 (https://download.01.org/0day-ci/archive/20231215/202312150759.RDeuSwNA-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20231215/202312150759.RDeuSwNA-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/202312150759.RDeuSwNA-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c:532:62-63: WARNING comparing pointer to 0

vim +532 drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c

   505	
   506	enum dmub_status dmub_srv_calc_mem_info(struct dmub_srv *dmub,
   507					       const struct dmub_srv_memory_params *params,
   508					       struct dmub_srv_fb_info *out)
   509	{
   510		uint8_t *cpu_base;
   511		uint64_t gpu_base;
   512		uint32_t i;
   513	
   514		if (!dmub->sw_init)
   515			return DMUB_STATUS_INVALID;
   516	
   517		memset(out, 0, sizeof(*out));
   518	
   519		if (params->region_info->num_regions != DMUB_NUM_WINDOWS)
   520			return DMUB_STATUS_INVALID;
   521	
   522		cpu_base = (uint8_t *)params->cpu_fb_addr;
   523		gpu_base = params->gpu_fb_addr;
   524	
   525		for (i = 0; i < DMUB_NUM_WINDOWS; ++i) {
   526			const struct dmub_region *reg =
   527				&params->region_info->regions[i];
   528	
   529			out->fb[i].cpu_addr = cpu_base + reg->base;
   530			out->fb[i].gpu_addr = gpu_base + reg->base;
   531	
 > 532			if (i == DMUB_WINDOW_4_MAILBOX && params->cpu_inbox_addr != 0) {
   533				out->fb[i].cpu_addr = (uint8_t *)params->cpu_inbox_addr + reg->base;
   534				out->fb[i].gpu_addr = params->gpu_inbox_addr + reg->base;
   535			}
   536	
   537			out->fb[i].size = reg->top - reg->base;
   538		}
   539	
   540		out->num_fb = DMUB_NUM_WINDOWS;
   541	
   542		return DMUB_STATUS_OK;
   543	}
   544	

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