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Date: Fri, 17 May 2024 18:17:09 +0300
From: Vladimir Oltean <olteanv@gmail.com>
To: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: netdev@vger.kernel.org, stephenlangstaff1@gmail.com,
	aleksander.lobakin@intel.com,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Alexander Lobakin <alobakin@pm.me>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net v2] net: Always descend into dsa/ folder with
 CONFIG_NET_DSA enabled
Message-ID: <20240517151709.tb65wut2ue76ghqs@skbuf>
References: <20240516165631.1929731-1-florian.fainelli@broadcom.com>
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In-Reply-To: <20240516165631.1929731-1-florian.fainelli@broadcom.com>

On Thu, May 16, 2024 at 09:56:30AM -0700, Florian Fainelli wrote:
> 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.
> 
> To preserve the intention of the original commit of limiting the amount
> of folder descending, conditionally descend into drivers/net/dsa when
> CONFIG_NET_DSA is enabled.
> 
> Fixes: 227d72063fcc ("dsa: simplify Kconfig symbols and dependencies")
> Reported-by: Stephen Langstaff <stephenlangstaff1@gmail.com>
> Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
> ---

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>