linux-kernel - Re: [PATCH v1 1/1] serial: core: Restore sysfs fwnode information

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Message-ID: <4b601513-5257-4511-95db-390791e17ba8@gmail.com>
Date: Thu, 18 Dec 2025 15:50:49 +0200
From: Cosmin Tanislav <demonsingur@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH v1 1/1] serial: core: Restore sysfs fwnode information



On 11/27/25 6:36 PM, Andy Shevchenko wrote:
> The change that restores sysfs fwnode information does it only for OF cases.
> Update the fix to cover all possible types of fwnodes.
> 
> Fixes: d36f0e9a0002 ("serial: core: restore of_node information in sysfs")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>   drivers/tty/serial/serial_base_bus.c | 10 ++++++----
>   1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
> index 22749ab0428a..8e891984cdc0 100644
> --- a/drivers/tty/serial/serial_base_bus.c
> +++ b/drivers/tty/serial/serial_base_bus.c
> @@ -13,7 +13,7 @@
>   #include <linux/device.h>
>   #include <linux/idr.h>
>   #include <linux/module.h>
> -#include <linux/of.h>
> +#include <linux/property.h>
>   #include <linux/serial_core.h>
>   #include <linux/slab.h>
>   #include <linux/spinlock.h>
> @@ -60,6 +60,7 @@ void serial_base_driver_unregister(struct device_driver *driver)
>   	driver_unregister(driver);
>   }
>   
> +/* On failure the caller must put device @dev with put_device() */
>   static int serial_base_device_init(struct uart_port *port,
>   				   struct device *dev,
>   				   struct device *parent_dev,
> @@ -73,7 +74,8 @@ static int serial_base_device_init(struct uart_port *port,
>   	dev->parent = parent_dev;
>   	dev->bus = &serial_base_bus_type;
>   	dev->release = release;
> -	device_set_of_node_from_dev(dev, parent_dev);
> +
> +	device_set_node(dev, fwnode_handle_get(dev_fwnode(parent_dev)));

device_set_of_node_from_dev() used to set dev->of_node_reused = true;
which made the pinctrl subsystem skip the logic inside
pinctrl_bind_pins().

Since you changed to device_set_node(), dev->of_node_reused is no longer
set to true and the following errors are issued because pinctrl will try
to request the same pins for all sub-devices.

> [    0.472463] pinctrl-rzt2h 802c0000.pinctrl: pin P27_4 already requested by 80005000.serial; cannot claim for 80005000.serial:0
> [    0.472485] pinctrl-rzt2h 802c0000.pinctrl: error -EINVAL: pin-220 (80005000.serial:0)
> [    0.472501] pinctrl-rzt2h 802c0000.pinctrl: error -EINVAL: could not request pin 220 (P27_4) from group sci0-pins on device pinctrl-rzt2h
> [    0.472515] ctrl 80005000.serial:0: Error applying setting, reverse things back
> [    0.472711] pinctrl-rzt2h 802c0000.pinctrl: pin P27_4 already requested by 80005000.serial; cannot claim for 80005000.serial:0.0
> [    0.472725] pinctrl-rzt2h 802c0000.pinctrl: error -EINVAL: pin-220 (80005000.serial:0.0)
> [    0.472738] pinctrl-rzt2h 802c0000.pinctrl: error -EINVAL: could not request pin 220 (P27_4) from group sci0-pins on device pinctrl-rzt2h
> [    0.472752] port 80005000.serial:0.0: Error applying setting, reverse things back

Maybe we should set

dev->of_node_reused = true;

manually right above the call to device_set_node(), grouped with the
rest of dev initialization?

>   
>   	if (!serial_base_initialized) {
>   		dev_dbg(port->dev, "uart_add_one_port() called before arch_initcall()?\n");
> @@ -94,7 +96,7 @@ static void serial_base_ctrl_release(struct device *dev)
>   {
>   	struct serial_ctrl_device *ctrl_dev = to_serial_base_ctrl_device(dev);
>   
> -	of_node_put(dev->of_node);
> +	fwnode_handle_put(dev_fwnode(dev));
>   	kfree(ctrl_dev);
>   }
>   
> @@ -142,7 +144,7 @@ static void serial_base_port_release(struct device *dev)
>   {
>   	struct serial_port_device *port_dev = to_serial_base_port_device(dev);
>   
> -	of_node_put(dev->of_node);
> +	fwnode_handle_put(dev_fwnode(dev));
>   	kfree(port_dev);
>   }
>