linux-kernel - Re: [PATCH V3 1/3] iommu/arm-smmu-v3: Add device-tree support for CMDQV driver

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Message-ID: <3be111a4-faa8-4a30-8638-d8e8db0f365d@nvidia.com>
Date: Fri, 5 Dec 2025 11:45:28 +0530
From: Ashish Mhetre <amhetre@...dia.com>
To: Robin Murphy <robin.murphy@....com>, will@...nel.org, nicolinc@...dia.com
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
 thierry.reding@...il.com, jonathanh@...dia.com, vdumpa@...dia.com,
 jgg@...pe.ca, linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-tegra@...r.kernel.org, conor+dt@...nel.org, krzk+dt@...nel.org,
 joro@...tes.org, robh@...nel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH V3 1/3] iommu/arm-smmu-v3: Add device-tree support for
 CMDQV driver


On 12/3/2025 9:19 PM, Robin Murphy wrote:
> External email: Use caution opening links or attachments
>
>
> On 2025-12-03 11:04 am, Ashish Mhetre wrote:
>>
>> On 12/3/2025 2:05 PM, kernel test robot wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> Hi Ashish,
>>>
>>> kernel test robot noticed the following build errors:
>>>
>>> [auto build test ERROR on next-20251201]
>>> [also build test ERROR on v6.18]
>>> [cannot apply to robh/for-next linus/master v6.18 v6.18-rc7 v6.18-rc6]
>>> [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/Ashish-Mhetre/
>>> iommu-arm-smmu-v3-Add-device-tree-support-for-CMDQV-
>>> driver/20251202-003517
>>> base:   next-20251201
>>> patch link: https://lore.kernel.org/r/20251201163219.3237266-2-
>>> amhetre%40nvidia.com
>>> patch subject: [PATCH V3 1/3] iommu/arm-smmu-v3: Add device-tree
>>> support for CMDQV driver
>>> config: arm64-allmodconfig (https://download.01.org/0day-ci/
>>> archive/20251203/202512031601.IpliwbHW-lkp@...el.com/config)
>>> compiler: clang version 19.1.7 (https://github.com/llvm/llvm-project
>>> cd708029e0b2869e80abe31ddb175f7c35361f90)
>>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/
>>> archive/20251203/202512031601.IpliwbHW-lkp@...el.com/reproduce)
>>>
>>> If you fix the issue in a separate patch/commit (i.e. not just a new
>>> version of
>>> the same patch/commit), kindly add following tags
>>> | Reported-by: kernel test robot <lkp@...el.com>
>>> | Closes: https://lore.kernel.org/oe-kbuild-all/202512031601.IpliwbHW-
>>> lkp@...el.com/
>>>
>>> All errors (new ones prefixed by >>):
>>>
>>>>> ld.lld: error: duplicate symbol: init_module
>>>     >>> defined at arm-smmu-v3.c
>>>     >>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.o:
>>> (init_module)
>>>     >>> defined at tegra241-cmdqv.c
>>>     >>> drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.o:
>>> (.init.text+0x4)
>>> -- 
>>>>> ld.lld: error: duplicate symbol: cleanup_module
>>>     >>> defined at arm-smmu-v3.c
>>>     >>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.o:
>>> (cleanup_module)
>>>     >>> defined at tegra241-cmdqv.c
>>>     >>> drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.o:
>>> (.exit.text+0x4)
>>
>> Hi Nic, Robin,
>>
>> How do you suggest fixing this? Is it fine to compile tegra241-cmdqv as
>> separate module
>> and export tegra241_cmdqv_probe() to fix this warning?
>
> As Jon just pointed out, the issue is using module_platform_driver(),
> which is unnecessary anyway since this is not a driver; nor is it even a
> module, it's just some extra code that can be included in the
> arm_smmu_v3 driver, and will be integral to the arm_smmu_v3.ko module if
> built as a such.
>
> You could sanity-check the compatible of the phandle target in
> tegra_cmdqv_dt_probe() if you feel like you should do more than just
> blindly trust the DT, but either way trying to register a dummy platform
> driver that won't bind to anything is pointless.
>

Thanks for the pointers Jon, Robin. I agree that this part of code is
redundant and can be removed. I will make these changes in next version.

>> I am using GCC compiler and was not able to reproduce this with W=1 
>> build.
>
> This will be happening with CONFIG_ARM_SMMU_V3=m.
>
> Thanks,
> Robin.
>
>>
>> Thanks,
>> Ashish Mhetre
>>
>>> -- 
>>> 0-DAY CI Kernel Test Service
>>> https://github.com/intel/lkp-tests/wiki
>