Re: [PATCH] net: dsa: ocelot: add NET_VENDOR_MICROSEMI dependency

From: Vladimir Oltean <olteanv@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Vladimir Oltean <vladimir.oltean@nxp.com>,
	Claudiu Manoil <claudiu.manoil@nxp.com>,
	"David S. Miller" <davem@davemloft.net>,
	Andrew Lunn <andrew@lunn.ch>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	netdev <netdev@vger.kernel.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: dsa: ocelot: add NET_VENDOR_MICROSEMI dependency
Date: Tue, 10 Dec 2019 23:37:13 +0200	[thread overview]
Message-ID: <CA+h21hrJ45J2N4DD=pAtE8vN6hCjUYUq5vz17pY-7=TpkA51rA@mail.gmail.com> (raw)
In-Reply-To: <20191210203710.2987983-1-arnd@arndb.de>

Hi Arnd,

On Tue, 10 Dec 2019 at 22:37, Arnd Bergmann <arnd@arndb.de> wrote:
>
> Selecting MSCC_OCELOT_SWITCH is not possible when NET_VENDOR_MICROSEMI
> is disabled:
>
> WARNING: unmet direct dependencies detected for MSCC_OCELOT_SWITCH
>   Depends on [n]: NETDEVICES [=y] && ETHERNET [=n] && NET_VENDOR_MICROSEMI [=n] && NET_SWITCHDEV [=y] && HAS_IOMEM [=y]
>   Selected by [m]:
>   - NET_DSA_MSCC_FELIX [=m] && NETDEVICES [=y] && HAVE_NET_DSA [=y] && NET_DSA [=y] && PCI [=y]
>
> Add a Kconfig dependency on NET_VENDOR_MICROSEMI, which also implies
> CONFIG_NETDEVICES.
>
> Fixes: 56051948773e ("net: dsa: ocelot: add driver for Felix switch family")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---

This has been submitted before, here [0].

It isn't wrong, but in principle I agree with David that it is strange
to put a "depends" relationship between a driver in drivers/net/dsa
and the Kconfig vendor umbrella from drivers/net/ethernet/mscc ("why
would the user care/need to enable NET_VENDOR_MICROSEMI to see the DSA
driver" is a valid point to me). This is mainly because I don't
understand the point of CONFIG_NET_VENDOR_* options, they're a bit
tribalistic to my ears.

Nonetheless, alternatives may be:
- Move MSCC_OCELOT_SWITCH core option outside of the
NET_VENDOR_MICROSEMI umbrella, and make it invisible to menuconfig,
just selectable from the 2 driver instances (MSCC_OCELOT_SWITCH_OCELOT
and NET_DSA_MSCC_FELIX). MSCC_OCELOT_SWITCH has no reason to be
selectable by the user anyway.
- Remove NET_VENDOR_MICROSEMI altogether. There is a single driver
under drivers/net/ethernet/mscc and it's already causing problems,
it's ridiculous.
- Leave it as it is. I genuinely ask: if the build system tells you
that the build dependencies are not met, does it matter if it compiles
or not?

[0]: https://www.spinics.net/lists/netdev/msg614325.html

Regards,
-Vladimir