Hi Dongdong, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on pci/next] [also build test WARNING on linuxtv-media/master linus/master v5.13-rc6 next-20210618] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Dongdong-Liu/PCI-Enable-10-Bit-t... base: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next config: s390-randconfig-r032-20210618 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 64720f57bea6a6bf033feef4a5751ab9c0c3b401) 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 s390 cross compiling tool for clang build # apt-get install binutils-s390x-linux-gnu # https://github.com/0day-ci/linux/commit/caefa7e6d0209bc08eb1934b58dae3aaa... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Dongdong-Liu/PCI-Enable-10-Bit-tag-support-for-PCIe-devices/20210617-041115 git checkout caefa7e6d0209bc08eb1934b58dae3aaa0b9dbba # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 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 >>): In file included from drivers/media/pci/cobalt/cobalt-driver.c:18: In file included from drivers/media/pci/cobalt/cobalt-driver.h:16: In file included from include/linux/pci.h:39: In file included from include/linux/io.h:13: In file included from arch/s390/include/asm/io.h:75: include/asm-generic/io.h:464:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __raw_readb(PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:477:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:36:59: note: expanded from macro '__le16_to_cpu' #define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x)) ^ include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16' #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x)) ^ In file included from drivers/media/pci/cobalt/cobalt-driver.c:18: In file included from drivers/media/pci/cobalt/cobalt-driver.h:16: In file included from include/linux/pci.h:39: In file included from include/linux/io.h:13: In file included from arch/s390/include/asm/io.h:75: include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr)); ~~~~~~~~~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32' #define __swab32(x) (__u32)__builtin_bswap32((__u32)(x)) ^ In file included from drivers/media/pci/cobalt/cobalt-driver.c:18: In file included from drivers/media/pci/cobalt/cobalt-driver.h:16: In file included from include/linux/pci.h:39: In file included from include/linux/io.h:13: In file included from arch/s390/include/asm/io.h:75: include/asm-generic/io.h:501:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writeb(value, PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:511:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:521:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr); ~~~~~~~~~~ ^ include/asm-generic/io.h:609:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:617:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:625:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] readsl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:634:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesb(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:643:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesw(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ include/asm-generic/io.h:652:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] writesl(PCI_IOBASE + addr, buffer, count); ~~~~~~~~~~ ^ capa, ^~~~ drivers/media/pci/cobalt/cobalt-driver.h:160:71: note: expanded from macro 'cobalt_info' #define cobalt_info(fmt, arg...) v4l2_info(&cobalt->v4l2_dev, fmt, ## arg) ^~~ include/media/v4l2-common.h:67:39: note: expanded from macro 'v4l2_info' v4l2_printk(KERN_INFO, dev, fmt , ## arg) ^~~ include/media/v4l2-common.h:58:44: note: expanded from macro 'v4l2_printk' printk(level "%s: " fmt, (dev)->name , ## arg) ^~~ drivers/media/pci/cobalt/cobalt-driver.c:189:10: note: initialize the variable 'capa' to silence this warning u32 capa; ^ = 0 13 warnings generated. vim +/capa +199 drivers/media/pci/cobalt/cobalt-driver.c 184 185 void cobalt_pcie_status_show(struct cobalt *cobalt) 186 { 187 struct pci_dev *pci_dev = cobalt->pci_dev; 188 struct pci_dev *pci_bus_dev = cobalt->pci_dev->bus->self; 189 u32 capa; 190 u16 stat, ctrl; 191 192 if (!pci_is_pcie(pci_dev) || !pci_is_pcie(pci_bus_dev)) 193 return; 194 195 /* Device */ 196 pcie_capability_read_word(pci_dev, PCI_EXP_DEVCTL, &ctrl); 197 pcie_capability_read_word(pci_dev, PCI_EXP_DEVSTA, &stat); 198 cobalt_info("PCIe device capability 0x%08x: Max payload %d\n", 200 get_payload_size(pci_dev->pcie_devcap & PCI_EXP_DEVCAP_PAYLOAD)); 201 cobalt_info("PCIe device control 0x%04x: Max payload %d. Max read request %d\n", 202 ctrl, 203 get_payload_size((ctrl & PCI_EXP_DEVCTL_PAYLOAD) >> 5), 204 get_payload_size((ctrl & PCI_EXP_DEVCTL_READRQ) >> 12)); 205 cobalt_info("PCIe device status 0x%04x\n", stat); 206 207 /* Link */ 208 pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &capa); 209 pcie_capability_read_word(pci_dev, PCI_EXP_LNKCTL, &ctrl); 210 pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &stat); 211 cobalt_info("PCIe link capability 0x%08x: %s per lane and %u lanes\n", 212 capa, get_link_speed(capa), 213 (capa & PCI_EXP_LNKCAP_MLW) >> 4); 214 cobalt_info("PCIe link control 0x%04x\n", ctrl); 215 cobalt_info("PCIe link status 0x%04x: %s per lane and %u lanes\n", 216 stat, get_link_speed(stat), 217 (stat & PCI_EXP_LNKSTA_NLW) >> 4); 218 219 /* Bus */ 220 pcie_capability_read_dword(pci_bus_dev, PCI_EXP_LNKCAP, &capa); 221 cobalt_info("PCIe bus link capability 0x%08x: %s per lane and %u lanes\n", 222 capa, get_link_speed(capa), 223 (capa & PCI_EXP_LNKCAP_MLW) >> 4); 224 225 /* Slot */ 226 pcie_capability_read_dword(pci_dev, PCI_EXP_SLTCAP, &capa); 227 pcie_capability_read_word(pci_dev, PCI_EXP_SLTCTL, &ctrl); 228 pcie_capability_read_word(pci_dev, PCI_EXP_SLTSTA, &stat); 229 cobalt_info("PCIe slot capability 0x%08x\n", capa); 230 cobalt_info("PCIe slot control 0x%04x\n", ctrl); 231 cobalt_info("PCIe slot status 0x%04x\n", stat); 232 } 233 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org