Hi Joerg, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 1e28eed17697bcf343c6743f0028cc3b5dd88bf0 commit: 56fbacc9bf23d372d78eef3809c1ac93d88e11f4 Merge branches 'arm/renesas', 'arm/qcom', 'arm/mediatek', 'arm/omap', 'arm/exynos', 'arm/smmu', 'ppc/pamu', 'x86/vt-d', 'x86/amd' and 'core' into next date: 8 months ago config: riscv-randconfig-r022-20210315 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 7ee96429a0b057bcc97331a6a762fc3cd00aed61) 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 # install riscv cross compiling tool for clang build # apt-get install binutils-riscv64-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 56fbacc9bf23d372d78eef3809c1ac93d88e11f4 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=riscv If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): priv->mapping = mapping; ^~~~~~~ drivers/gpu/drm/exynos/exynos_drm_dma.c:136:16: note: initialize the variable 'mapping' to silence this warning void *mapping; ^ = NULL 1 warning generated. vim +/mapping +146 drivers/gpu/drm/exynos/exynos_drm_dma.c 237556962e5115 Andrzej Hajda 2018-10-12 120 07dc3678bacc2a Marek Szyprowski 2020-03-09 121 int exynos_drm_register_dma(struct drm_device *drm, struct device *dev, 07dc3678bacc2a Marek Szyprowski 2020-03-09 122 void **dma_priv) 237556962e5115 Andrzej Hajda 2018-10-12 123 { 237556962e5115 Andrzej Hajda 2018-10-12 124 struct exynos_drm_private *priv = drm->dev_private; 237556962e5115 Andrzej Hajda 2018-10-12 125 237556962e5115 Andrzej Hajda 2018-10-12 126 if (!priv->dma_dev) { 237556962e5115 Andrzej Hajda 2018-10-12 127 priv->dma_dev = dev; 237556962e5115 Andrzej Hajda 2018-10-12 128 DRM_INFO("Exynos DRM: using %s device for DMA mapping operations\n", 237556962e5115 Andrzej Hajda 2018-10-12 129 dev_name(dev)); 237556962e5115 Andrzej Hajda 2018-10-12 130 } 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 131 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 132 if (!IS_ENABLED(CONFIG_EXYNOS_IOMMU)) 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 133 return 0; 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 134 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 135 if (!priv->mapping) { 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 136 void *mapping; 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 137 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 138 if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 139 mapping = arm_iommu_create_mapping(&platform_bus_type, 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 140 EXYNOS_DEV_ADDR_START, EXYNOS_DEV_ADDR_SIZE); 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 141 else if (IS_ENABLED(CONFIG_IOMMU_DMA)) 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 142 mapping = iommu_get_domain_for_dev(priv->dma_dev); 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 143 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 144 if (IS_ERR(mapping)) 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 145 return PTR_ERR(mapping); 67fbf3a3ef8443 Andrzej Hajda 2018-10-12 @146 priv->mapping = mapping; 237556962e5115 Andrzej Hajda 2018-10-12 147 } 237556962e5115 Andrzej Hajda 2018-10-12 148 07dc3678bacc2a Marek Szyprowski 2020-03-09 149 return drm_iommu_attach_device(drm, dev, dma_priv); 237556962e5115 Andrzej Hajda 2018-10-12 150 } 237556962e5115 Andrzej Hajda 2018-10-12 151 :::::: The code at line 146 was first introduced by commit :::::: 67fbf3a3ef84436c58b5ead53b4b866125ad7ce9 drm/exynos/iommu: merge IOMMU and DMA code :::::: TO: Andrzej Hajda <a.hajda(a)samsung.com&gt; :::::: CC: Inki Dae <inki.dae(a)samsung.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org