Re: [PATCH v6 3/9] v4l: platform: Add Renesas CEU driver

[kbuild test robot]

Hi Jacopo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v4.15-rc8]
[cannot apply to linuxtv-media/master next-20180119]
[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/Jacopo-Mondi/Renesas-Capture-Engine-Unit-CEU-V4L2-driver/20180120-053007
config: mn10300-allmodconfig (attached as .config)
compiler: am33_2.0-linux-gcc (GCC) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=mn10300 

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 >>):

   In file included from include/linux/scatterlist.h:9:0,
                    from include/linux/dma-mapping.h:11,
                    from drivers/media/platform/renesas-ceu.c:16:
   drivers/media/platform/renesas-ceu.c: In function 'ceu_start_streaming':
>> arch/mn10300/include/asm/io.h:63:25: warning: 'cdwdr' may be used uninitialized in this function [-Wmaybe-uninitialized]
     *(volatile u32 *) addr = b;
     ~~~~~~~~~~~~~~~~~~~~~~~^~~
   drivers/media/platform/renesas-ceu.c:335:27: note: 'cdwdr' was declared here
     u32 camcr, cdocr, cfzsr, cdwdr, capwr;
                              ^~~~~
   In file included from include/linux/scatterlist.h:9:0,
                    from include/linux/dma-mapping.h:11,
                    from drivers/media/platform/renesas-ceu.c:16:
>> arch/mn10300/include/asm/io.h:63:25: warning: 'cfzsr' may be used uninitialized in this function [-Wmaybe-uninitialized]
     *(volatile u32 *) addr = b;
     ~~~~~~~~~~~~~~~~~~~~~~~^~~
   drivers/media/platform/renesas-ceu.c:335:20: note: 'cfzsr' was declared here
     u32 camcr, cdocr, cfzsr, cdwdr, capwr;
                       ^~~~~
   drivers/media/platform/renesas-ceu.c:415:8: warning: 'camcr' may be used uninitialized in this function [-Wmaybe-uninitialized]
     camcr |= mbus_flags & V4L2_MBUS_HSYNC_ACTIVE_LOW ? 1 << 0 : 0;
     ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/media/platform/renesas-ceu.c:335:6: note: 'camcr' was declared here
     u32 camcr, cdocr, cfzsr, cdwdr, capwr;
         ^~~~~
   drivers/media/platform/renesas-ceu.c: In function 'ceu_probe':
   drivers/media/platform/renesas-ceu.c:1621:9: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return ret;
            ^~~
--
   In file included from include/linux/scatterlist.h:9:0,
                    from include/linux/dma-mapping.h:11,
                    from drivers/media//platform/renesas-ceu.c:16:
   drivers/media//platform/renesas-ceu.c: In function 'ceu_start_streaming':
>> arch/mn10300/include/asm/io.h:63:25: warning: 'cdwdr' may be used uninitialized in this function [-Wmaybe-uninitialized]
     *(volatile u32 *) addr = b;
     ~~~~~~~~~~~~~~~~~~~~~~~^~~
   drivers/media//platform/renesas-ceu.c:335:27: note: 'cdwdr' was declared here
     u32 camcr, cdocr, cfzsr, cdwdr, capwr;
                              ^~~~~
   In file included from include/linux/scatterlist.h:9:0,
                    from include/linux/dma-mapping.h:11,
                    from drivers/media//platform/renesas-ceu.c:16:
>> arch/mn10300/include/asm/io.h:63:25: warning: 'cfzsr' may be used uninitialized in this function [-Wmaybe-uninitialized]
     *(volatile u32 *) addr = b;
     ~~~~~~~~~~~~~~~~~~~~~~~^~~
   drivers/media//platform/renesas-ceu.c:335:20: note: 'cfzsr' was declared here
     u32 camcr, cdocr, cfzsr, cdwdr, capwr;
                       ^~~~~
   drivers/media//platform/renesas-ceu.c:415:8: warning: 'camcr' may be used uninitialized in this function [-Wmaybe-uninitialized]
     camcr |= mbus_flags & V4L2_MBUS_HSYNC_ACTIVE_LOW ? 1 << 0 : 0;
     ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/media//platform/renesas-ceu.c:335:6: note: 'camcr' was declared here
     u32 camcr, cdocr, cfzsr, cdwdr, capwr;
         ^~~~~
   drivers/media//platform/renesas-ceu.c: In function 'ceu_probe':
   drivers/media//platform/renesas-ceu.c:1621:9: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return ret;
            ^~~

vim +/cdwdr +63 arch/mn10300/include/asm/io.h

b920de1b include/asm-mn10300/io.h David Howells 2008-02-08  60  
b920de1b include/asm-mn10300/io.h David Howells 2008-02-08  61  static inline void writel(u32 b, volatile void __iomem *addr)
b920de1b include/asm-mn10300/io.h David Howells 2008-02-08  62  {
b920de1b include/asm-mn10300/io.h David Howells 2008-02-08 @63  	*(volatile u32 *) addr = b;
b920de1b include/asm-mn10300/io.h David Howells 2008-02-08  64  }
b920de1b include/asm-mn10300/io.h David Howells 2008-02-08  65  

:::::: The code at line 63 was first introduced by commit
:::::: b920de1b77b72ca9432ac3f97edb26541e65e5dd mn10300: add the MN10300/AM33 architecture to the kernel

:::::: TO: David Howells <dhowells@xxxxxxxxxx>
:::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxxxxxxxx>

---
0-DAY kernel test infrastructure                Open Source Technology Center
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