Re: [PATCH net] net: Always descend into dsa/ folder

[Alexander Lobakin <aleksander.lobakin@intel.com>]

From: Florian Fainelli <florian.fainelli@broadcom.com>
Date: Wed, 15 May 2024 20:33:45 -0700

> Stephen reported that he was unable to get the dsa_loop driver to get
> probed, and the reason ended up being because he had CONFIG_FIXED_PHY=y
> in his kernel configuration. As Masahiro explained it:
> 
>   "obj-m += dsa/" means everything under dsa/ must be modular.
> 
>   If there is a built-in object under dsa/ with CONFIG_NET_DSA=m,
>   you cannot do  "obj-$(CONFIG_NET_DSA) += dsa/".
> 
>   You need to change it back to "obj-y += dsa/".
> 
> This was the case here whereby CONFIG_NET_DSA=m, and so the
> obj-$(CONFIG_FIXED_PHY) += dsa_loop_bdinfo.o rule is not executed and
> the DSA loop mdio_board info structure is not registered with the
> kernel, and eventually the device is simply not found.
> 
> Fixes: 227d72063fcc ("dsa: simplify Kconfig symbols and dependencies")
> Reported-by: Stephen Langstaff <stephenlangstaff1@gmail.com>
> Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
> ---
>  drivers/net/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index 9c053673d6b2..0f6f0f091e0e 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -49,7 +49,7 @@ obj-$(CONFIG_MHI_NET) += mhi_net.o
>  obj-$(CONFIG_ARCNET) += arcnet/
>  obj-$(CONFIG_CAIF) += caif/
>  obj-$(CONFIG_CAN) += can/
> -obj-$(CONFIG_NET_DSA) += dsa/
> +obj-y += dsa/

obj-$(CONFIG_NET_DSA:m=y) += dsa/

?

or

ifdef CONFIG_NET_DSA
obj-y += dsa/
endif

I don't like always adding folders even if nothing will be built there
as we then have a lot of folders with just empty built-in.a.

>  obj-$(CONFIG_ETHERNET) += ethernet/
>  obj-$(CONFIG_FDDI) += fddi/
>  obj-$(CONFIG_HIPPI) += hippi/

Thanks,
Olek