Re: drivers/pci/controller/cadence/pci-j721e.c:648:undefined reference to `cdns_pcie_host_disable'

[Siddharth Vadapalli <s-vadapalli@ti.com>]

On 11/11/25 7:39 PM, Manivannan Sadhasivam wrote:
> On Tue, Nov 11, 2025 at 05:09:25PM +0530, Siddharth Vadapalli wrote:
>> On Tue, 2025-11-11 at 16:24 +0530, Manivannan Sadhasivam wrote:
>>
>> Hello Mani,
>>
>>> + Siddharth
>>
>> Thank you for notifying me of this.
>>
>>>
>>> On Tue, Nov 11, 2025 at 05:28:54PM +0800, kernel test robot wrote:
>>>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>>>> head:   4427259cc7f7571a157fbc9b5011e1ef6fe0a4a8
>>>> commit: 1c72774df028429836eec3394212f2921bb830fc PCI: sg2042: Add Sophgo SG2042 PCIe driver
>>>> date:   8 weeks ago
>>>> config: loongarch-randconfig-r113-20251110 (https://download.01.org/0day-ci/archive/20251111/202511111705.MZ7ls8Hm-lkp@intel.com/config)
>>>> compiler: loongarch64-linux-gcc (GCC) 15.1.0
>>>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251111/202511111705.MZ7ls8Hm-lkp@intel.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@intel.com>
>>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202511111705.MZ7ls8Hm-lkp@intel.com/
>>>>
>>>> All errors (new ones prefixed by >>):
>>>>
>>>>     loongarch64-linux-ld: drivers/pci/controller/cadence/pci-j721e.o: in function `j721e_pcie_remove':
>>>>>> drivers/pci/controller/cadence/pci-j721e.c:648:(.text+0x83c): undefined reference to `cdns_pcie_host_disable'
>>>>
>>>
>>>  From .config:
>>>
>>> CONFIG_PCIE_CADENCE=y
>>> CONFIG_PCIE_CADENCE_HOST=m
>>> CONFIG_PCIE_CADENCE_EP=y
>>> CONFIG_PCIE_CADENCE_PLAT=y
>>> # CONFIG_PCIE_CADENCE_PLAT_HOST is not set
>>> CONFIG_PCIE_CADENCE_PLAT_EP=y
>>> CONFIG_PCIE_SG2042_HOST=m
>>> CONFIG_PCI_J721E=y
>>> # CONFIG_PCI_J721E_HOST is not set
>>> CONFIG_PCI_J721E_EP=y
>>>
>>> PCI_J721E selects PCIE_CADENCE_HOST only if PCI_J721E_HOST is selected,
>>> otherwise, it will not select it. This will take care of the dependency between
>>> PCI_J721E and PCIE_CADENCE_{HOST/EP}.
>>>
>>> But if PCIE_CADENCE_HOST is selected as a module by other drivers like,
>>> CONFIG_PCIE_SG2042_HOST=m, then if PCI_J721E is selected as a built-in using
>>> CONFIG_PCI_J721E_EP=y, it results in this build error as the built-in driver
>>> becomes dependent on a symbol from a loadable module.
>>
>> While I don't deny the build error associated with the above config, it is
>> an invalid config in the sense that the Glue drivers for two different
>> devices are being enabled. This seems to be a generic issue wherein
>> multiple drivers tend to depend on a library/common driver. How is it
>> handled in such cases?
> 
> AFAIK, the common library should be built-in to avoid issues like this.

Ok. If that is the usual approach then I have no objections to it.

> 
>> Is there a notion of reordering configs to ensure that such build errors
>> are avoided?
>>
>> If PCI_J721E_EP was selected as 'y' before 'PCI_SG2042_HOST' being selected
>> as 'm', it would have resulted in 'PCIE_CADENCE_EP' being selected as 'y'
>> and this won't cause a build error even with 'PCI_SG2042_HOST' selected as
>> 'm'.
>>
>>>
>>> I guess, we should force PCIE_CADENCE_{HOST/EP} to be 'bool' as it is getting
>>> selected by multiple drivers.
>>
>> This will defeat the purpose of the series that enabled loadable module
>> support for the pci-j721e.c driver and the pcie-cadence-host/ep.c drivers.
>>
> 
> Your 'pci-j721e.c' can still be a loadable module, only the common library will
> be built-in, which is not that bad.

Yes, this will work.

Please let me know if you want me to post the patch to update 
CONFIG_PCIE_CADENCE_{EP/HOST} to a bool.

Regards,
Siddharth.