netdev - Re: [PATCH] net: phy: fixed-phy: Drop GPIO from fixed_phy

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Date:   Tue, 15 Jan 2019 02:46:04 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH] net: phy: fixed-phy: Drop GPIO from fixed_phy_add()

On Mon, Jan 14, 2019 at 09:02:25AM +0100, Linus Walleij wrote:
> All users of the fixed_phy_add() pass -1 as GPIO number
> to the fixed phy driver, and all users of fixed_phy_register()
> pass -1 as GPIO number as well, except for the device
> tree MDIO bus.
> 
> Any new users should create a proper device and pass the
> GPIO as a descriptor associated with the device so delete
> the GPIO argument from the calls and drop the code looking
> requesting a GPIO in fixed_phy_add().
> 
> In fixed phy_register(), investigate the "fixed-link"
> node and pick the GPIO descriptor from "link-gpios" if
> this property exists. Move the corresponding code out
> of of_mdio.c as the fixed phy code anyways requires
> OF to be in use.
> 
> Signed-off-by: Linus Walleij <linus.walleij@...aro.org>

Hi Linus

I tested on the zii-devel-b, which i think is the only mainline board
using a GPIO. So

Tested-by: Andrew Lunn <andrew@...n.ch>

> +int fixed_phy_add(unsigned int irq, int phy_addr,
> +		  struct fixed_phy_status *status) {
> +	return fixed_phy_add_gpiod(irq, phy_addr, status, NULL);
>  }

This seems like the sort of wrapper function which could go in the
header file. At lease please add a blank line.

> +#ifdef CONFIG_OF_GPIO
> +static struct gpio_desc *fixed_phy_get_gpiod(struct device_node *np)
> +{
> +	struct device_node *fixed_link_node;
> +	struct gpio_desc *gpiod;
> +
> +	if (!np)
> +		return NULL;
> +
> +	fixed_link_node = of_get_child_by_name(np, "fixed-link");
> +	if (!fixed_link_node)
> +		return NULL;
> +
> +	/*
> +	 * As the fixed link is just a device tree node without any
> +	 * Linux device associated with it, we simply have to rip out
> +	 * the GPIO descriptor from the device tree like this.

I don't really like the "rip it out". It makes it sound like the
binding is doing something wrong. It is not. Switches are complex
devices and need a complex binding to describe the hardware.

> +	 */
> +	gpiod = gpiod_get_from_of_node(fixed_link_node, "link-gpios", 0,
> +				       GPIOD_IN, "mdio");
> +	of_node_put(fixed_link_node);
> +	if (IS_ERR(gpiod)) {
> +		/* Just return and bail on deferrals */
> +		if (PTR_ERR(gpiod) == -EPROBE_DEFER)
> +			return gpiod;

I'm not sure the comment is adding much here. This is pretty much
normal handling of EPROBE_DEFER.

> +		pr_err("error getting GPIO for fixed link, proceed without\n");

It would be nice to use %pOF to print fixed_link_node. There can be
multiple fixed_link devices and knowing which one failed could be
useful.

Thanks
	Andrew