linux-kernel - [PATCH] i3c: fix module_i3c_i2c

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Message-Id: <20250725090609.2456262-1-arnd@kernel.org>
Date: Fri, 25 Jul 2025 11:06:03 +0200
From: Arnd Bergmann <arnd@...nel.org>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Boris Brezillon <bbrezillon@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Frank Li <Frank.Li@....com>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	linux-i3c@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] i3c: fix module_i3c_i2c_driver() with I3C=n

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>
---
 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))
-- 
2.39.5