Re: [PATCH v2] net: enetc: fix the netc-lib driver build dependency

[Vladimir Oltean <vladimir.oltean@nxp.com>]

Hi Wei,

On Thu, Jun 05, 2025 at 02:08:36PM +0800, Wei Fang wrote:
> The kernel robot reported the following errors when the netc-lib driver
> was compiled as a loadable module and the enetc-core driver was built-in.
> 
> ld.lld: error: undefined symbol: ntmp_init_cbdr
> referenced by enetc_cbdr.c:88 (drivers/net/ethernet/freescale/enetc/enetc_cbdr.c:88)
> ld.lld: error: undefined symbol: ntmp_free_cbdr
> referenced by enetc_cbdr.c:96 (drivers/net/ethernet/freescale/enetc/enetc_cbdr.c:96)
> 
> Simply changing "tristate" to "bool" can fix this issue, but considering
> that the netc-lib driver needs to support being compiled as a loadable
> module and LS1028 does not need the netc-lib driver. Therefore, we add a
> boolean symbol 'NXP_NTMP' to enable 'NXP_NETC_LIB' as needed. And when
> adding NETC switch driver support in the future, there is no need to
> modify the dependency, just select "NXP_NTMP" and "NXP_NETC_LIB" at the
> same time.
> 
> Reported-by: Arnd Bergmann <arnd@kernel.org>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202505220734.x6TF6oHR-lkp@intel.com/
> Fixes: 4701073c3deb ("net: enetc: add initial netc-lib driver to support NTMP")
> Suggested-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Wei Fang <wei.fang@nxp.com>
> ---
> v1 Link: https://lore.kernel.org/imx/20250603105056.4052084-1-wei.fang@nxp.com/
> v2:
> 1. Add the boolean symbol 'NXP_NTMP' as Arnd suggested and modify
> the commit message.
> ---
>  drivers/net/ethernet/freescale/enetc/Kconfig | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/freescale/enetc/Kconfig b/drivers/net/ethernet/freescale/enetc/Kconfig
> index e917132d3714..54b0f0a5a6bb 100644
> --- a/drivers/net/ethernet/freescale/enetc/Kconfig
> +++ b/drivers/net/ethernet/freescale/enetc/Kconfig
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  config FSL_ENETC_CORE
>  	tristate
> +	select NXP_NETC_LIB if NXP_NTMP
>  	help
>  	  This module supports common functionality between the PF and VF
>  	  drivers for the NXP ENETC controller.
> @@ -22,6 +23,9 @@ config NXP_NETC_LIB
>  	  Switch, such as NETC Table Management Protocol (NTMP) 2.0, common tc
>  	  flower and debugfs interfaces and so on.
>  
> +config NXP_NTMP
> +	bool
> +
>  config FSL_ENETC
>  	tristate "ENETC PF driver"
>  	depends on PCI_MSI
> @@ -45,7 +49,7 @@ config NXP_ENETC4
>  	select FSL_ENETC_CORE
>  	select FSL_ENETC_MDIO
>  	select NXP_ENETC_PF_COMMON
> -	select NXP_NETC_LIB
> +	select NXP_NTMP
>  	select PHYLINK
>  	select DIMLIB
>  	help
> -- 
> 2.34.1
>

I think you slightly misunderstood Arnd's suggestion. NXP_NTMP was named
"NXP_NETC_NTMP" in his proposal, and it meant "does FSL_ENETC_CORE need
the functionality from NXP_NETC_LIB?".

The switch driver shouldn't need to select NXP_NTMP. Just NXP_NETC_LIB.

I don't agree with removing "NETC" from NXP_NETC_NTMP, I think it helps
clarify that the option pertains just to the NETC drivers.