linux-kernel - Re: [PATCH v4 06/23] mailbox: Allow controller specific mapping using fwnode

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Message-ID: <aDWk5kIN3lkB0Jw2@smile.fi.intel.com>
Date: Tue, 27 May 2025 14:41:26 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Anup Patel <apatel@...tanamicro.com>
Cc: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jassi Brar <jassisinghbrar@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Uwe Kleine-König <ukleinek@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Len Brown <lenb@...nel.org>, Sunil V L <sunilvl@...tanamicro.com>,
	Rahul Pathak <rpathak@...tanamicro.com>,
	Leyfoon Tan <leyfoon.tan@...rfivetech.com>,
	Atish Patra <atish.patra@...ux.dev>,
	Andrew Jones <ajones@...tanamicro.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Anup Patel <anup@...infault.org>, linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 06/23] mailbox: Allow controller specific mapping
 using fwnode

On Sun, May 25, 2025 at 02:16:53PM +0530, Anup Patel wrote:
> Introduce optional fw_node() callback which allows a mailbox controller
> driver to provide controller specific mapping using fwnode.
> 
> The Linux OF framework already implements fwnode operations for the
> Linux DD framework so the fw_xlate() callback works fine with device
> tree as well.

...

>  struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
>  {
> +	struct fwnode_reference_args fwspec;

+ property.h (if not done yet)

> -	int ret;
> +	int i, ret;

Why is 'i' signed?

> -	if (!dev || !dev->of_node) {
> -		pr_debug("%s: No owner device node\n", __func__);
> +	if (!dev || !dev->fwnode) {

Do not dereference fwnode directly. Use dev_fwnode.

> +		pr_debug("%s: No owner %s\n", __func__, !dev ? "device" : "fwnode");

Use positive conditional.

__func__ is redundant it debug messages. With Dynamic Debug enabled it may be
switched at run-time.

>  		return ERR_PTR(-ENODEV);
>  	}
>  
> -	ret = of_parse_phandle_with_args(dev->of_node, "mboxes", "#mbox-cells",
> -					 index, &spec);
> +	ret = fwnode_property_get_reference_args(dev->fwnode, "mboxes",

	struct fwnode_handle *fwnode = dev_fwnode(dev);

> +						 "#mbox-cells", 0, index, &fwspec);
>  	if (ret) {
>  		dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
>  		return ERR_PTR(ret);
>  	}

> +	memset(&spec, 0, sizeof(spec));
> +	if (dev->of_node) {

What is this check for?

> +		spec.np = to_of_node(fwspec.fwnode);
> +		spec.args_count = fwspec.nargs;
> +		for (i = 0; i < spec.args_count; i++)
> +			spec.args[i] = fwspec.args[i];
> +	}
> +
>  	mutex_lock(&con_mutex);
>  
>  	chan = ERR_PTR(-EPROBE_DEFER);
> -	list_for_each_entry(mbox, &mbox_cons, node)
> -		if (mbox->dev->of_node == spec.np) {
> +	list_for_each_entry(mbox, &mbox_cons, node) {
> +		if (mbox->fw_xlate && mbox->dev->fwnode == fwspec.fwnode) {
> +			chan = mbox->fw_xlate(mbox, &fwspec);
> +			if (!IS_ERR(chan))
> +				break;
> +		} else if (mbox->of_xlate && mbox->dev->of_node == spec.np) {
>  			chan = mbox->of_xlate(mbox, &spec);
>  			if (!IS_ERR(chan))
>  				break;
>  		}


		if (!IS_ERR(...))
			break;

is common.


> +	}

...

> +fw_mbox_index_xlate(struct mbox_controller *mbox,
> +		    const struct fwnode_reference_args *sp)

One line?

-- 
With Best Regards,
Andy Shevchenko