Hi Suravee,

I love your patch! Perhaps something to improve:

[auto build test WARNING on awilliam-vfio/for-linus]
[also build test WARNING on linus/master v6.2-rc3 next-20230110]
[cannot apply to joro-iommu/next awilliam-vfio/next]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Suravee-Suthikulpanit/iommu-amd-Introduce-Protection-domain-flag-VFIO/20230110-223527
base:   https://github.com/awilliam/linux-vfio.git for-linus
patch link:    https://lore.kernel.org/r/20230110143137.54517-2-suravee.suthikulpanit%40amd.com
patch subject: [PATCH 1/4] iommu/amd: Introduce Protection-domain flag VFIO
config: x86_64-defconfig
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/ea80bf7e918395d3445c0114fee20997512a4ccf
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Suravee-Suthikulpanit/iommu-amd-Introduce-Protection-domain-flag-VFIO/20230110-223527
        git checkout ea80bf7e918395d3445c0114fee20997512a4ccf
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/iommu/amd/

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

All warnings (new ones prefixed by >>):

   drivers/iommu/amd/iommu.c: In function 'amd_iommu_detach_device':
>> drivers/iommu/amd/iommu.c:2136:35: warning: unused variable 'domain' [-Wunused-variable]
    2136 |         struct protection_domain *domain = to_pdomain(dom);
         |                                   ^~~~~~


vim +/domain +2136 drivers/iommu/amd/iommu.c

  2131	
  2132	static void amd_iommu_detach_device(struct iommu_domain *dom,
  2133					    struct device *dev)
  2134	{
  2135		struct iommu_dev_data *dev_data = dev_iommu_priv_get(dev);
> 2136		struct protection_domain *domain = to_pdomain(dom);
  2137		struct amd_iommu *iommu;
  2138	
  2139		if (!check_device(dev))
  2140			return;
  2141	
  2142		if (dev_data->domain != NULL)
  2143			detach_device(dev);
  2144	
  2145		iommu = rlookup_amd_iommu(dev);
  2146		if (!iommu)
  2147			return;
  2148	

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