linux-kernel - Re: [PATCH] i3c: fix module_i3c_i2c_driver() with I3C=n

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Message-ID: <aIOGa1ILK9ySlzQS@lizhi-Precision-Tower-5810>
Date: Fri, 25 Jul 2025 09:28:11 -0400
From: Frank Li <Frank.li@....com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: Arnd Bergmann <arnd@...nel.org>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Boris Brezillon <bbrezillon@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i3c: fix module_i3c_i2c_driver() with I3C=n

On Fri, Jul 25, 2025 at 02:19:19AM -0700, Guenter Roeck wrote:
> On 7/25/25 02:06, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@...db.de>
> >
> > When CONFIG_I3C is disabled and the i3c_i2c_driver_register() happens
> > to not be inlined, any driver calling it still references the i3c_driver
> > instance, which then causes a link failure:
> >
> > x86_64-linux-ld: drivers/hwmon/lm75.o: in function `lm75_i3c_reg_read':
> > lm75.c:(.text+0xc61): undefined reference to `i3cdev_to_dev'
> > x86_64-linux-ld: lm75.c:(.text+0xd25): undefined reference to `i3c_device_do_priv_xfers'
> > x86_64-linux-ld: lm75.c:(.text+0xdd8): undefined reference to `i3c_device_do_priv_xfers'
> >
> > This issue was part of the original i3c code, but only now caused problems
> > when i3c support got added to lm75.
> >
> > Change the 'inline' annotations in the header to '__always_inline' to
> > ensure that the dead-code-elimination pass in the compiler can optimize
> > it out as intended.
> >
> > Fixes: 6071d10413ff ("hwmon: (lm75) add I3C support for P3T1755")
> > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Frank Li <Frank.Li@....com>

>
> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
>
> > ---
> >   include/linux/i3c/device.h | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/i3c/device.h b/include/linux/i3c/device.h
> > index b674f64d0822..7f136de4b73e 100644
> > --- a/include/linux/i3c/device.h
> > +++ b/include/linux/i3c/device.h
> > @@ -245,7 +245,7 @@ void i3c_driver_unregister(struct i3c_driver *drv);
> >    *
> >    * Return: 0 if both registrations succeeds, a negative error code otherwise.
> >    */
> > -static inline int i3c_i2c_driver_register(struct i3c_driver *i3cdrv,
> > +static __always_inline int i3c_i2c_driver_register(struct i3c_driver *i3cdrv,
> >   					  struct i2c_driver *i2cdrv)
> >   {
> >   	int ret;
> > @@ -270,7 +270,7 @@ static inline int i3c_i2c_driver_register(struct i3c_driver *i3cdrv,
> >    * Note that when CONFIG_I3C is not enabled, this function only unregisters the
> >    * @i2cdrv.
> >    */
> > -static inline void i3c_i2c_driver_unregister(struct i3c_driver *i3cdrv,
> > +static __always_inline void i3c_i2c_driver_unregister(struct i3c_driver *i3cdrv,
> >   					     struct i2c_driver *i2cdrv)
> >   {
> >   	if (IS_ENABLED(CONFIG_I3C))
>
>
> --
> linux-i3c mailing list
> linux-i3c@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-i3c

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