Re: drivers/power/reset/nvmem-reboot-mode.c:27:42: error: passing argument 2 of 'nvmem_cell_write' from incompatible pointer type

[Nandor Han <nandor.han@vaisala.com>]

On 8/11/19 2:43 AM, kbuild test robot wrote:
> Hi Han,
> 
> FYI, the error/warning still remains.
> 
> tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   dcbb4a153971ff8646af0c963f5698bf21bfbfdc
> commit: 7a78a7f7695bf9ef9cef3c06fbc5fa4573fd0eef power: reset: nvmem-reboot-mode: use NVMEM as reboot mode write interface
> date:   7 weeks ago
> config: x86_64-randconfig-d003-201932 (attached as .config)
> compiler: gcc-7 (Debian 7.4.0-10) 7.4.0
> reproduce:
>          git checkout 7a78a7f7695bf9ef9cef3c06fbc5fa4573fd0eef
>          # save the attached .config to linux build tree
>          make ARCH=x86_64
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
>     drivers/power/reset/nvmem-reboot-mode.c: In function 'nvmem_reboot_mode_write':
>>> drivers/power/reset/nvmem-reboot-mode.c:27:42: error: passing argument 2 of 'nvmem_cell_write' from incompatible pointer type [-Werror=incompatible-pointer-types]
>       ret = nvmem_cell_write(nvmem_rbm->cell, &magic, sizeof(magic));
>                                               ^
>     In file included from drivers/power/reset/nvmem-reboot-mode.c:10:0:
>     include/linux/nvmem-consumer.h:120:19: note: expected 'const char *' but argument is of type 'unsigned int *'
>      static inline int nvmem_cell_write(struct nvmem_cell *cell,
>                        ^~~~~~~~~~~~~~~~
>     cc1: some warnings being treated as errors
> 
> vim +/nvmem_cell_write +27 drivers/power/reset/nvmem-reboot-mode.c
> 
>      18	
>      19	static int nvmem_reboot_mode_write(struct reboot_mode_driver *reboot,
>      20					    unsigned int magic)
>      21	{
>      22		int ret;
>      23		struct nvmem_reboot_mode *nvmem_rbm;
>      24	
>      25		nvmem_rbm = container_of(reboot, struct nvmem_reboot_mode, reboot);
>      26	
>    > 27		ret = nvmem_cell_write(nvmem_rbm->cell, &magic, sizeof(magic));
>      28		if (ret < 0)
>      29			dev_err(reboot->dev, "update reboot mode bits failed\n");
>      30	
>      31		return ret;
>      32	}
>      33	
> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
> 

Hi,

Seems that `nvmem-consumer.h` declares a different signature for 
`nvmem_cell_write` method depending on `CONFIG_NVMEM` configuration:

#if IS_ENABLED(CONFIG_NVMEM)

...

int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len);

...

#else

...
static inline int nvmem_cell_write(struct nvmem_cell *cell,
                                     const char *buf, size_t len)
{
         return -EOPNOTSUPP;
}

...

#endif /* CONFIG_NVMEM *

What's the best approach here?

Nandor