Re: [PATCH 01/12] net: dsa: lantiq_gswip: mark OF related data as maybe unused

From: Vladimir Oltean <olteanv@gmail.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Hauke Mehrtens <hauke@hauke-m.de>,
	Woojung Huh <woojung.huh@microchip.com>,
	UNGLinuxDriver@microchip.com,
	Claudiu Manoil <claudiu.manoil@nxp.com>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Colin Foster <colin.foster@in-advantage.com>,
	Michael Hennerich <michael.hennerich@analog.com>,
	Alexander Aring <alex.aring@gmail.com>,
	Stefan Schmidt <stefan@datenfreihafen.org>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-wpan@vger.kernel.org
Subject: Re: [PATCH 01/12] net: dsa: lantiq_gswip: mark OF related data as maybe unused
Date: Sun, 12 Mar 2023 12:57:29 +0200	[thread overview]
Message-ID: <20230312105729.bnxn4a6mf2gav7ym@skbuf> (raw)
In-Reply-To: <d9b197c8-56fe-b59d-5fca-bc863ac1e7ed@linaro.org>

On Sun, Mar 12, 2023 at 11:20:38AM +0100, Krzysztof Kozlowski wrote:
> On 11/03/2023 19:14, Vladimir Oltean wrote:
> > On Sat, Mar 11, 2023 at 06:32:52PM +0100, Krzysztof Kozlowski wrote:
> >> The driver can be compile tested with !CONFIG_OF making certain data
> >> unused:
> >>
> >>   drivers/net/dsa/lantiq_gswip.c:1888:34: error: ‘xway_gphy_match’ defined but not used [-Werror=unused-const-variable=]
> >>
> >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >> ---
> > 
> > Do you happen to have any context as to why of_match_node() without
> > CONFIG_OF is implemented as:
> > 
> > #define of_match_node(_matches, _node)	NULL
> > 
> > and not as:
> > 
> > static inline const struct of_device_id *
> > of_match_node(const struct of_device_id *matches,
> > 	      const struct device_node *node)
> > {
> > 	return NULL;
> > }
> > 
> > ?
> > 
> > Generally, the static inline shim function model is nicer, because it
> > allows us to not scatter __maybe_unused all around.
> 
> Sorry, I don't follow. I don't touch that wrappers, just fix errors
> related to OF device ID tables, although in few cases it is indeed
> related to of_match_node.

I'm saying this because in lantiq_gswip.c, xway_gphy_match is accessed
through of_match_node(). If the shim definition for of_match_node() was
different, the variable wouldn't have been unused with CONFIG_OF=n.
I guess it's worth considering changing that wrapper instead of adding
the __maybe_unused.