Re: [PATCH v5 2/3] platform/x86: dell-uart-backlight: Bind through normal serdev matching

[Markus Probst <markus.probst@posteo.de>]

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On Sat, 2026-10-24 at 20:04 +0800, ChunAn Wu wrote:
> The driver creates a serdev client without firmware metadata and
> force-attaches its driver to it.
> 
> Pass the modalias to serdev_device_add() and give the serdev driver a
> matching id_table, so that the serdev core binds the two through normal
> matching, then drop the manual attachment.
> 
> The client now also reports a "serial:dell_uart_backlight" modalias to
> userspace instead of failing with -ENODEV. A failing serdev probe no
> longer propagates out of the platform probe; as for any other bus, the
> client is simply left unbound.
> 
> Signed-off-by: ChunAn Wu <an.wu@canonical.com>
> ---
>  .../platform/x86/dell/dell-uart-backlight.c    | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell/dell-uart-backlight.c b/drivers/platform/x86/dell/dell-uart-backlight.c
> index f323a667dc2d..9b8ef91bb0a2 100644
> --- a/drivers/platform/x86/dell/dell-uart-backlight.c
> +++ b/drivers/platform/x86/dell/dell-uart-backlight.c
> @@ -325,11 +325,17 @@ static int dell_uart_bl_serdev_probe(struct serdev_device *serdev)
>  	return PTR_ERR_OR_ZERO(dell_bl->bl);
>  }
>  
> +static const struct serdev_device_id dell_uart_bl_serdev_id[] = {
> +	{ KBUILD_MODNAME },
> +	{ }
> +};
> +
>  static struct serdev_device_driver dell_uart_bl_serdev_driver = {
>  	.probe = dell_uart_bl_serdev_probe,
>  	.driver = {
>  		.name = KBUILD_MODNAME,
>  	},
> +	.id_table = dell_uart_bl_serdev_id,
>  };
>  
>  static int dell_uart_bl_pdev_probe(struct platform_device *pdev)
> @@ -354,7 +360,7 @@ static int dell_uart_bl_pdev_probe(struct platform_device *pdev)
>  	if (!serdev)
>  		return -ENOMEM;
>  
> -	ret = serdev_device_add(serdev);
> +	ret = serdev_device_add(serdev, KBUILD_MODNAME);
>  	if (ret) {
>  		dev_err(&pdev->dev, "error %d adding serdev\n", ret);
>  		serdev_device_put(serdev);
> @@ -365,20 +371,10 @@ static int dell_uart_bl_pdev_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto err_remove_serdev;
>  
> -	/*
> -	 * serdev device <-> driver matching relies on OF or ACPI matches and
> -	 * neither is available here, manually bind the driver.
> -	 */
> -	ret = device_driver_attach(&dell_uart_bl_serdev_driver.driver, &serdev->dev);
> -	if (ret)
> -		goto err_unregister_serdev_driver;
> -
>  	/* So that dell_uart_bl_pdev_remove() can remove the serdev */
>  	platform_set_drvdata(pdev, serdev);
>  	return 0;
>  
> -err_unregister_serdev_driver:
> -	serdev_device_driver_unregister(&dell_uart_bl_serdev_driver);
>  err_remove_serdev:
>  	serdev_device_remove(serdev);
>  	return ret;

Reviewed-by: Markus Probst <markus.probst@posteo.de>

Thanks
- Markus Probst

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