sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[kernel test robot]

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Hi Sven,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   bbf5c979011a099af5dc76498918ed7df445635b
commit: 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b ASoC: Add initial ZL38060 driver
date:   6 months ago
config: x86_64-randconfig-r001-20201012 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 9e72d3eaf38f217698f72cb8fdc969a6e72dad3a)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids' [-Wunused-const-variable]
   static const struct of_device_id zl38_dt_ids[] = {
                                    ^
   1 warning generated.

vim +/zl38_dt_ids +614 sound/soc/codecs/zl38060.c

   613	
 > 614	static const struct of_device_id zl38_dt_ids[] = {
   615		{ .compatible = "mscc,zl38060", },
   616		{ /* sentinel */ }
   617	};
   618	MODULE_DEVICE_TABLE(of, zl38_dt_ids);
   619	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
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sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[kernel test robot]

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Hi Sven,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   8404c9fbc84b741f66cff7d4934a25dd2c344452
commit: 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b ASoC: Add initial ZL38060 driver
date:   1 year ago
config: x86_64-randconfig-a001-20210506 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 8f5a2a5836cc8e4c1def2bdeb022e7b496623439)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids' [-Wunused-const-variable]
   static const struct of_device_id zl38_dt_ids[] = {
                                    ^
   1 warning generated.


vim +/zl38_dt_ids +614 sound/soc/codecs/zl38060.c

   613	
 > 614	static const struct of_device_id zl38_dt_ids[] = {
   615		{ .compatible = "mscc,zl38060", },
   616		{ /* sentinel */ }
   617	};
   618	MODULE_DEVICE_TABLE(of, zl38_dt_ids);
   619	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
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sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[kernel test robot]

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Hi Sven,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   eb5f95f1593f7c22dac681b19e815828e2af3efd
commit: 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b ASoC: Add initial ZL38060 driver
date:   5 months ago
config: x86_64-randconfig-a012-20200920 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project ed79827aea444e6995fb3d36abc2bfd36331773c)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids' [-Wunused-const-variable]
   static const struct of_device_id zl38_dt_ids[] = {
                                    ^
   1 warning generated.

# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
vim +/zl38_dt_ids +614 sound/soc/codecs/zl38060.c

   613	
 > 614	static const struct of_device_id zl38_dt_ids[] = {
   615		{ .compatible = "mscc,zl38060", },
   616		{ /* sentinel */ }
   617	};
   618	MODULE_DEVICE_TABLE(of, zl38_dt_ids);
   619	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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Re: sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[Sven Van Asbroeck]

Hi Nathan and Mark,

On Fri, Jul 10, 2020 at 11:30 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> Sure, you could hide it behind an ifdef for either CONFIG_OF or MODULE
> (since you could build this as a module with CONFIG_OF disabled).
>
> I just figured this would be something frowned upon but if that is how
> you would prefer it to be fixed, then I have no objections to it.
>

That's how things used to work in the past: we had to #ifdef CONFIG_OF
all the driver of_XXX code, so it could be built on !CONFIG_OF.

I remember problems with this approach: it generated a lot of
visual noise, it was fragile in both directions: including too much,
and excluding too much. Last but not least, it required us ARM people
to test build each patch on !CONFIG_OF, which many conveniently forgot
to do :)

My "vote" would be to fix the warning using compiler magic. For
example:

#if !CONFIG_OF
// #define of_match_ptr(x) NULL
#define of_match_ptr(x) ((x) == NULL ? NULL : NULL)
#endif

That seems to eliminate the warning on my gcc version 7.5.0, but of
course as compilers get more clever, this could eventually
generate a warning (if it doesn't already on clang).

So perhaps use compiler attributes instead?

Stand-alone testable code snippet below.
======================================================

// gcc -Wall unused.c
// results in: match_table is NULL
// gcc -Wall -DCONFIG_OF unused.c
// results in: match_table[0] = 5

#include <stdio.h>

#ifdef CONFIG_OF
#define of_match_ptr(x) x
#else
#define of_match_ptr(x) ((x) == NULL ? NULL : NULL)
#endif

struct of_device_id {
    int id;
};

static const struct of_device_id some_ids[] = {
    { .id = 5, },
    { /* sentinel */ }
};

struct driver {
    const struct of_device_id *of_match_table;
};

static const struct driver my_driver = {
    .of_match_table = of_match_ptr(some_ids),
};

int main()
{
    if (my_driver.of_match_table)
        printf("match_table[0] = %d\n", my_driver.of_match_table[0].id);
    else
        printf("match_table is NULL\n");
}

Re: sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[Nathan Chancellor]

On Fri, Jul 10, 2020 at 01:24:59PM +0100, Mark Brown wrote:
> On Thu, Jul 09, 2020 at 07:41:00PM -0700, Nathan Chancellor wrote:
> 
> > When CONFIG_SND_SOC_ZL38060 is y, MODULE_DEVICE_TABLE expands to nothing
> > so zl38_dt_ids will be unused. This is a pretty common construct in the
> > kernel and the only way I can think of to resolve this through the code
> > is by adding __used annotations to all of these variables, which I think
> > is overkill for this.
> 
> > Personally, I think this warning should be downgraded to W=2, thoughts?
> 
> We've had that warning available for ever, we shouldn't need to disable
> it now.  I had thought there was supposed to be magic which caused
> of_match_ptr() to make things look referenced when !OF but don't seem to
> actually see any sign of it.  The other thing is to just have ifdefs
> around the table.

While it has been available, it's been hidden behind W=1, which is now
default on for 0day.

Sure, you could hide it behind an ifdef for either CONFIG_OF or MODULE
(since you could build this as a module with CONFIG_OF disabled).

I just figured this would be something frowned upon but if that is how
you would prefer it to be fixed, then I have no objections to it.

Cheers,
Nathan

Re: sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[Mark Brown]

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On Thu, Jul 09, 2020 at 07:41:00PM -0700, Nathan Chancellor wrote:

> When CONFIG_SND_SOC_ZL38060 is y, MODULE_DEVICE_TABLE expands to nothing
> so zl38_dt_ids will be unused. This is a pretty common construct in the
> kernel and the only way I can think of to resolve this through the code
> is by adding __used annotations to all of these variables, which I think
> is overkill for this.

> Personally, I think this warning should be downgraded to W=2, thoughts?

We've had that warning available for ever, we shouldn't need to disable
it now.  I had thought there was supposed to be magic which caused
of_match_ptr() to make things look referenced when !OF but don't seem to
actually see any sign of it.  The other thing is to just have ifdefs
around the table.

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Re: sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[Nathan Chancellor]

On Fri, Jul 10, 2020 at 12:47:31AM +0800, kernel test robot wrote:
> Hi Sven,
> 
> FYI, the error/warning still remains.
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   0bddd227f3dc55975e2b8dfa7fc6f959b062a2c7
> commit: 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b ASoC: Add initial ZL38060 driver
> date:   3 months ago
> config: x86_64-randconfig-r004-20200709 (attached as .config)
> compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 02946de3802d3bc65bc9f2eb9b8d4969b5a7add8)
> 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 x86_64 cross compiling tool for clang build
>         # apt-get install binutils-x86-64-linux-gnu
>         git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):
> 
> >> sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids' [-Wunused-const-variable]
>    static const struct of_device_id zl38_dt_ids[] = {
>                                     ^
>    1 warning generated.
> 
> vim +/zl38_dt_ids +614 sound/soc/codecs/zl38060.c
> 
>    613	
>  > 614	static const struct of_device_id zl38_dt_ids[] = {
>    615		{ .compatible = "mscc,zl38060", },
>    616		{ /* sentinel */ }
>    617	};
>    618	MODULE_DEVICE_TABLE(of, zl38_dt_ids);
>    619	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
> 

When CONFIG_SND_SOC_ZL38060 is y, MODULE_DEVICE_TABLE expands to nothing
so zl38_dt_ids will be unused. This is a pretty common construct in the
kernel and the only way I can think of to resolve this through the code
is by adding __used annotations to all of these variables, which I think
is overkill for this.

Personally, I think this warning should be downgraded to W=2, thoughts?

Cheers,
Nathan

sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[kernel test robot]

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Hi Sven,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   0bddd227f3dc55975e2b8dfa7fc6f959b062a2c7
commit: 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b ASoC: Add initial ZL38060 driver
date:   3 months ago
config: x86_64-randconfig-r004-20200709 (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 02946de3802d3bc65bc9f2eb9b8d4969b5a7add8)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids' [-Wunused-const-variable]
   static const struct of_device_id zl38_dt_ids[] = {
                                    ^
   1 warning generated.

vim +/zl38_dt_ids +614 sound/soc/codecs/zl38060.c

   613	
 > 614	static const struct of_device_id zl38_dt_ids[] = {
   615		{ .compatible = "mscc,zl38060", },
   616		{ /* sentinel */ }
   617	};
   618	MODULE_DEVICE_TABLE(of, zl38_dt_ids);
   619	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[kernel test robot]

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Hi Sven,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   dcb7fd82c75ee2d6e6f9d8cc71c52519ed52e258
commit: 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b ASoC: Add initial ZL38060 driver
date:   3 months ago
config: x86_64-randconfig-a012-20200706 (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project a378c0449507e00e96534ff9ce9034e185425182)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids' [-Wunused-const-variable]
   static const struct of_device_id zl38_dt_ids[] = {
                                    ^
   1 warning generated.

vim +/zl38_dt_ids +614 sound/soc/codecs/zl38060.c

   613	
 > 614	static const struct of_device_id zl38_dt_ids[] = {
   615		{ .compatible = "mscc,zl38060", },
   616		{ /* sentinel */ }
   617	};
   618	MODULE_DEVICE_TABLE(of, zl38_dt_ids);
   619	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids'

[kernel test robot]

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Hi Sven,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   69119673bd50b176ded34032fadd41530fb5af21
commit: 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b ASoC: Add initial ZL38060 driver
date:   8 weeks ago
config: x86_64-randconfig-r003-20200617 (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 487ca07fcc75d52755c9fe2ee05bcb3b6eeeec44)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        git checkout 52e8a94baf9026276fcdc9ff21a50dc2ca0bc94b
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>, old ones prefixed by <<):

>> sound/soc/codecs/zl38060.c:614:34: warning: unused variable 'zl38_dt_ids' [-Wunused-const-variable]
static const struct of_device_id zl38_dt_ids[] = {
^
1 warning generated.

vim +/zl38_dt_ids +614 sound/soc/codecs/zl38060.c

   613	
 > 614	static const struct of_device_id zl38_dt_ids[] = {
   615		{ .compatible = "mscc,zl38060", },
   616		{ /* sentinel */ }
   617	};
   618	MODULE_DEVICE_TABLE(of, zl38_dt_ids);
   619	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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