Re: [PATCH] serial: max310x: fix I2C-only build

[Hugo Villeneuve]

Hi Anrnd,

On Tue, 19 May 2026 22:34:25 +0200
Arnd Bergmann <arnd@xxxxxxxxxx> wrote:

> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> Allowing the driver to be built when CONFIG_SPI_MASTER is turned off
> now causes build failures:

A few days ago i sent v2 of a patch to fix this problem:

https://lore.kernel.org/all/20260515183217.3554037-1-hugo@xxxxxxxxxxx/raw

Did you saw it?


> 
> drivers/tty/serial/max310x.c: In function 'max310x_uart_init':
> drivers/tty/serial/max310x.c:1737:32: error: 'max310x_spi_driver' undeclared (first use in this function); did you mean 'max310x_i2c_driver'?
>  1737 |         spi_unregister_driver(&max310x_spi_driver);
>       |                                ^~~~~~~~~~~~~~~~~~
>       |                                max310x_i2c_driver
> drivers/tty/serial/max310x.c:1737:32: note: each undeclared identifier is reported only once for each function it appears in
> drivers/tty/serial/max310x.c:1740:1: error: label 'err_spi_register' defined but not used [-Werror=unused-label]
>  1740 | err_spi_register:
>       | ^~~~~~~~~~~~~~~~
> drivers/tty/serial/max310x.c: At top level:
> drivers/tty/serial/max310x.c:1502:29: error: 'regcfg' defined but not used [-Werror=unused-variable]
>  1502 | static struct regmap_config regcfg = {
>       |                             ^~~~~~
> 
> While fixing this, I ran into another problem with I2C=m, which
> previously would just not use I2C support.
> 
> Fix the #ifdef checks to handle all combinations correctly, and
> change the Kconfig dependency to ensure that the driver cannot
> be built-in when I2C=m.
> 
> Fixes: 20ffe4b3330a ("serial: max310x: allow driver to be built with SPI or I2C")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  drivers/tty/serial/Kconfig   |  1 +
>  drivers/tty/serial/max310x.c | 40 +++++++++++++++++++-----------------
>  2 files changed, 22 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 811250bbbd39..b9b40e80ea81 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -323,6 +323,7 @@ config SERIAL_MAX3100
>  config SERIAL_MAX310X
>  	tristate "MAX310X support"
>  	depends on SPI_MASTER || I2C
> +	depends on I2C || !I2C
>  	select SERIAL_CORE
>  	select REGMAP_SPI if SPI_MASTER
>  	select REGMAP_I2C if I2C
> diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
> index 5168490a1cbb..042ae962c1f6 100644
> --- a/drivers/tty/serial/max310x.c
> +++ b/drivers/tty/serial/max310x.c
> @@ -1499,6 +1499,20 @@ static const struct of_device_id __maybe_unused max310x_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, max310x_dt_ids);
>  
> +static const char *max310x_regmap_name(u8 port_id)
> +{
> +	switch (port_id) {
> +	case 0:	return "port0";
> +	case 1:	return "port1";
> +	case 2:	return "port2";
> +	case 3:	return "port3";
> +	default:
> +		WARN_ON(true);
> +		return NULL;
> +	}
> +}
> +
> +#ifdef CONFIG_SPI_MASTER
>  static struct regmap_config regcfg = {
>  	.reg_bits = 8,
>  	.val_bits = 8,
> @@ -1514,20 +1528,6 @@ static struct regmap_config regcfg = {
>  	.max_raw_write = MAX310X_FIFO_SIZE,
>  };
>  
> -static const char *max310x_regmap_name(u8 port_id)
> -{
> -	switch (port_id) {
> -	case 0:	return "port0";
> -	case 1:	return "port1";
> -	case 2:	return "port2";
> -	case 3:	return "port3";
> -	default:
> -		WARN_ON(true);
> -		return NULL;
> -	}
> -}
> -
> -#ifdef CONFIG_SPI_MASTER
>  static int max310x_spi_extended_reg_enable(struct device *dev, bool enable)
>  {
>  	struct max310x_port *s = dev_get_drvdata(dev);
> @@ -1598,7 +1598,7 @@ static struct spi_driver max310x_spi_driver = {
>  };
>  #endif
>  
> -#ifdef CONFIG_I2C
> +#if IS_ENABLED(CONFIG_I2C)
>  static int max310x_i2c_extended_reg_enable(struct device *dev, bool enable)
>  {
>  	return 0;
> @@ -1724,7 +1724,7 @@ static int __init max310x_uart_init(void)
>  		goto err_spi_register;
>  #endif
>  
> -#ifdef CONFIG_I2C
> +#if IS_ENABLED(CONFIG_I2C)
>  	ret = i2c_add_driver(&max310x_i2c_driver);
>  	if (ret)
>  		goto err_i2c_register;
> @@ -1732,12 +1732,14 @@ static int __init max310x_uart_init(void)
>  
>  	return 0;
>  
> -#ifdef CONFIG_I2C
> +#if IS_ENABLED(CONFIG_I2C)
>  err_i2c_register:
> +#endif
> +#ifdef CONFIG_SPI_MASTER
>  	spi_unregister_driver(&max310x_spi_driver);
> +err_spi_register:
>  #endif
>  
> -err_spi_register:
>  	uart_unregister_driver(&max310x_uart);
>  
>  	return ret;
> @@ -1746,7 +1748,7 @@ module_init(max310x_uart_init);
>  
>  static void __exit max310x_uart_exit(void)
>  {
> -#ifdef CONFIG_I2C
> +#if IS_ENABLED(CONFIG_I2C)
>  	i2c_del_driver(&max310x_i2c_driver);
>  #endif
>  
> -- 
> 2.39.5
> 
> 
> 


-- 
Hugo Villeneuve