linux-kernel - Re: [RFC PATCH 1/2] serial: core: Move tty and serdev to be children of serial core port device

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Date:   Tue, 24 Oct 2023 15:17:26 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Rob Herring <robh@...nel.org>, Dhruva Gole <d-gole@...com>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        John Ogness <john.ogness@...utronix.de>,
        Johan Hovold <johan@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        Maximilian Luz <luzmaximilian@...il.com>
Subject: Re: [RFC PATCH 1/2] serial: core: Move tty and serdev to be children
 of serial core port device

On Tue, Oct 24, 2023 at 02:36:18PM +0300, Tony Lindgren wrote:
> Let's move tty and serdev controller to be children of the serial core port
> device. This way the runtime PM usage count of a child device propagates
> to the serial hardware device.
> 
> The tty and serdev devices are associated with a specific serial port of
> a serial hardware controller device, and we now have serial core hierarchy
> of controllers and ports.
> 
> The tty device moves happily with just a change of the parent device.
> The serdev device init needs some changes to separate the serial hardware
> controller device from the parent device.

...

> -	ctrl->dev.of_node = parent->of_node;
> +	ctrl->dev.of_node = host->of_node;

Even above should have been using device_set_node(&ctrl->dev, dev_fwnode(host)).

...

>  	/* Make sure controller and ResourceSource handle match */
> -	if (ACPI_HANDLE(ctrl->dev.parent) != lookup.controller_handle)
> +	if (ACPI_HANDLE(ctrl->host) != lookup.controller_handle)

This can be changed to use device_match_acpi_handle().

>  		return -ENODEV;

...

> -	if (!has_acpi_companion(ctrl->dev.parent))
> +	if (!has_acpi_companion(ctrl->host))

I prefer is_acpi_device_node(dev_fwnode(...)) check, but here seems no other
use for fwnode (haven't checked the full context, though).

>  		return -ENODEV;

-- 
With Best Regards,
Andy Shevchenko