Kernel 6.10-rc1 b,Build error with [PATCH v5 2/3] serial: port: Add support of PNP IRQ

[Woody Suwalski <terraluna977@gmail.com>]

Guanbing Huang wrote:
> From: Guanbing Huang <albanhuang@tencent.com>
>
> The function __uart_read_properties doesn't cover PNP devices, so add IRQ
> processing for PNP devices in the branch.
>
> Signed-off-by: Guanbing Huang <albanhuang@tencent.com>
> Suggested-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> Reviewed-by: Bing Fan <tombinfan@tencent.com>
> Tested-by: Linheng Du <dylanlhdu@tencent.com>
> ---
> v4 -> v5: change "pnp" and "irq" in the commit message to uppercase, modify the subject
>            to start with "serial: port:", modify the location of the header file pnp.h
>
>   drivers/tty/serial/serial_port.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/serial_port.c b/drivers/tty/serial/serial_port.c
> index 22b9eeb23e68..8504bae1d2c9 100644
> --- a/drivers/tty/serial/serial_port.c
> +++ b/drivers/tty/serial/serial_port.c
> @@ -11,6 +11,7 @@
>   #include <linux/of.h>
>   #include <linux/platform_device.h>
>   #include <linux/pm_runtime.h>
> +#include <linux/pnp.h>
>   #include <linux/property.h>
>   #include <linux/serial_core.h>
>   #include <linux/spinlock.h>
> @@ -221,7 +222,11 @@ static int __uart_read_properties(struct uart_port *port, bool use_defaults)
>   
>   	if (dev_is_platform(dev))
>   		ret = platform_get_irq(to_platform_device(dev), 0);
> -	else
> +	else if (dev_is_pnp(dev)) {
> +		ret = pnp_irq(to_pnp_dev(dev), 0);
> +		if (ret < 0)
> +			ret = -ENXIO;
> +	} else
>   		ret = fwnode_irq_get(dev_fwnode(dev), 0);
>   	if (ret == -EPROBE_DEFER)
>   		return ret;

Hello all, trying to build 6.10-rc1 fails for me in serial_base.o:
   CALL    scripts/checksyscalls.sh
   DESCEND objtool
   INSTALL libsubcmd_headers
   CC [M]  drivers/tty/serial/serial_port.o
   LD [M]  drivers/tty/serial/serial_base.o
   MODPOST Module.symvers
ERROR: modpost: "pnp_bus_type" [drivers/tty/serial/serial_base.ko] 
undefined!
make[2]: *** [scripts/Makefile.modpost:145: Module.symvers] Error 1
make[1]: *** 
[/woody/src/kernels/linux-6.10-pingu/work/linux-6.10/Makefile:1892: 
modpost] Error 2
make: *** [Makefile:246: __sub-make] Error 2

Reversing the patch "fixes" the problem :-(
I am building on a Debian bookworm system, gcc 12.2

Any suggestions  how to make it work?

Thanks, Woody