linux-kernel - drivers/iommu/mtk_iommu.c:438:29: warning: comparison is always false due to limited range of data type

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Message-ID: <202006221907.TuIvC5eP%lkp@intel.com>
Date:   Mon, 22 Jun 2020 19:03:12 +0800
From:   kernel test robot <lkp@...el.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Joerg Roedel <jroedel@...e.de>
Subject: drivers/iommu/mtk_iommu.c:438:29: warning: comparison is always
 false due to limited range of data type

Hi Krzysztof,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   625d3449788f85569096780592549d0340e9c0c7
commit: e93a1695d7fb551376b1c1220a267d032b6ad159 iommu: Enable compile testing for some of drivers
date:   4 months ago
config: i386-randconfig-r012-20200622 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
reproduce (this is a W=1 build):
        git checkout e93a1695d7fb551376b1c1220a267d032b6ad159
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

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

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

drivers/iommu/mtk_iommu.c: In function 'mtk_iommu_iova_to_phys':
>> drivers/iommu/mtk_iommu.c:438:29: warning: comparison is always false due to limited range of data type [-Wtype-limits]
438 |  if (data->enable_4GB && pa >= MTK_IOMMU_4GB_MODE_REMAP_BASE)
|                             ^~

vim +438 drivers/iommu/mtk_iommu.c

4d689b61944589 Robin Murphy 2017-09-28  429  
0df4fabe208d95 Yong Wu      2016-02-23  430  static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
0df4fabe208d95 Yong Wu      2016-02-23  431  					  dma_addr_t iova)
0df4fabe208d95 Yong Wu      2016-02-23  432  {
0df4fabe208d95 Yong Wu      2016-02-23  433  	struct mtk_iommu_domain *dom = to_mtk_domain(domain);
30e2fccf951238 Yong Wu      2017-08-21  434  	struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
0df4fabe208d95 Yong Wu      2016-02-23  435  	phys_addr_t pa;
0df4fabe208d95 Yong Wu      2016-02-23  436  
0df4fabe208d95 Yong Wu      2016-02-23  437  	pa = dom->iop->iova_to_phys(dom->iop, iova);
b4dad40e4f35bb Yong Wu      2019-08-24 @438  	if (data->enable_4GB && pa >= MTK_IOMMU_4GB_MODE_REMAP_BASE)
b4dad40e4f35bb Yong Wu      2019-08-24  439  		pa &= ~BIT_ULL(32);
30e2fccf951238 Yong Wu      2017-08-21  440  
0df4fabe208d95 Yong Wu      2016-02-23  441  	return pa;
0df4fabe208d95 Yong Wu      2016-02-23  442  }
0df4fabe208d95 Yong Wu      2016-02-23  443  

:::::: The code at line 438 was first introduced by commit
:::::: b4dad40e4f35bbf2393f35f4492acf799eb8136d iommu/mediatek: Adjust the PA for the 4GB Mode

:::::: TO: Yong Wu <yong.wu@...iatek.com>
:::::: CC: Joerg Roedel <jroedel@...e.de>

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

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