On Wed, 7 Dec 2022, Tony Lindgren wrote:
> We want to enable runtime PM for serial port device drivers in a generic
> way. To do this, we want to have the serial core layer manage the
> registered physical serial controller devices.
>
> To do this, let's set up a struct device for the serial core controller
> as suggested by Greg and Jiri. The serial core controller devices are
> children of the physical serial port device. The serial core controller
> device is needed to support multiple different kind of ports connected
> to single physical serial port device.
>
> Let's also set up a struct device for the serial core port. The serial
> core port instances are children of the serial core controller device.
> With the serial core port device we can now flush pending TX on the
> runtime PM resume as suggested by Johan.
>
> Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Suggested-by: Jiri Slaby <jirislaby@xxxxxxxxxx>
> Suggested-by: Johan Hovold <johan@xxxxxxxxxx>
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> ---
>
> Changes since v3:
>
> - Simplify things by adding a serial core control device as the child of
> the physical serial port as suggested by Jiri
>
> - Drop the tinkering of the physical serial port device for runtime PM.
> Serial core just needs to manage port->port_dev with the addition of
> the serial core control device and the device hierarchy will keep the
> pysical serial port device enabled as needed
>
> - Simplify patch description with all the runtime PM tinkering gone
>
> - Coding style improvments as noted by Andy
>
> - Post as a single RFC patch as we're close to the merge window
>
> Changes since v2:
>
> - Make each serial port a proper device as suggested by Greg. This is
> a separate patch that flushes the TX on runtime PM resume
>
> Changes since v1:
>
> - Use kref as suggested by Andy
>
> - Fix memory leak on error as noted by Andy
>
> - Use use unsigned char for supports_autosuspend as suggested by Andy
>
> - Coding style improvments as suggested by Andy
>
> ---
> + ret = serial_core_add_one_port(drv, port);
> + if (ret)
> + return ret;
> +
> + mutex_lock(&port_mutex);
> +
> + /* Inititalize a serial core controller device if needed */
> + ctrl_dev = serial_core_ctrl_find(drv, port->dev, port->ctrl_id);
> + if (!ctrl_dev) {
> + ctrl_dev = serial_core_ctrl_device_add(port);
> + if (!ctrl_dev)
> + goto err_remove_port;
> + allocated = true;
> + }
> +
> + /* Initialize a serial core port device */
> + ret = serial_core_port_device_add(ctrl_dev, port);
How is ->port_dev supposed to work here?
->port_dev is not set until in serial_core_port_device_add() but you made
serial_core_add_one_port() call before that.
--
i.
> + if (ret)
> + goto err_del_ctrl_dev;
> +
> + mutex_unlock(&port_mutex);
> +
> + return 0;
> +
> +err_del_ctrl_dev:
> + if (allocated)
> + platform_device_del(to_platform_device(ctrl_dev));
> +
> +err_remove_port:
> + mutex_unlock(&port_mutex);
> +
> + return serial_core_remove_one_port(drv, port);
> +}
> +EXPORT_SYMBOL_NS(serial_core_register_port, SERIAL_CORE);
