[Intel-gfx] [PATCH v6 7/8] drm/i915: Decode system memory bandwidth

[kbuild test robot]

Hi Mahesh,

[auto build test WARNING on next-20161123]
[cannot apply to drm-intel/for-linux-next v4.9-rc6 v4.9-rc5 v4.9-rc4 v4.9-rc6]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Mahesh-Kumar/GEN-9-Arbitrated-Bandwidth-WM-WA-s-IPC/20161124-172826
config: x86_64-randconfig-x012-201647 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/i915/i915_drv.c: In function 'i915_driver_load':
>> drivers/gpu/drm/i915/i915_drv.c:1049:47: warning: 'ch1_rank' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (ch0_rank == DRAM_RANK_SINGLE || ch1_rank == DRAM_RANK_SINGLE)
                                         ~~~~~~~~~^~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/i915/i915_drv.c:1013:22: note: 'ch1_rank' was declared here
     enum rank ch0_rank, ch1_rank;
                         ^~~~~~~~
>> drivers/gpu/drm/i915/i915_drv.c:1049:15: warning: 'ch0_rank' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (ch0_rank == DRAM_RANK_SINGLE || ch1_rank == DRAM_RANK_SINGLE)
         ~~~~~~~~~^~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/i915/i915_drv.c:1013:12: note: 'ch0_rank' was declared here
     enum rank ch0_rank, ch1_rank;
               ^~~~~~~~

vim +/ch1_rank +1049 drivers/gpu/drm/i915/i915_drv.c

  1033			return -EINVAL;
  1034		}
  1035	
  1036		memdev_info->bandwidth_kbps = (memdev_info->num_channels *
  1037								mem_freq_khz * 8);
  1038	
  1039		if (memdev_info->bandwidth_kbps == 0) {
  1040			DRM_ERROR("Couldn't get system memory bandwidth\n");
  1041			return -EINVAL;
  1042		}
  1043		memdev_info->valid = true;
  1044	
  1045		/*
  1046		 * If any of channel is single rank channel,
  1047		 * consider single rank memory
  1048		 */
> 1049		if (ch0_rank == DRAM_RANK_SINGLE || ch1_rank == DRAM_RANK_SINGLE)
  1050			memdev_info->rank = DRAM_RANK_SINGLE;
  1051		else
  1052			memdev_info->rank = max(ch0_rank, ch1_rank);
  1053	
  1054		return 0;
  1055	}
  1056	
  1057	static int

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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