netdev - Re: [PATCH v1 1/2] net: mdio: Add the reset function for IPQ MDIO driver

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Message-ID: <YQ/3ycEU9zkn8idJ@lunn.ch>
Date:   Sun, 8 Aug 2021 17:27:05 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Luo Jie <luoj@...eaurora.org>
Cc:     hkallweit1@...il.com, davem@...emloft.net, kuba@...nel.org,
        linux@...linux.org.uk, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, sricharan@...eaurora.org
Subject: Re: [PATCH v1 1/2] net: mdio: Add the reset function for IPQ MDIO
 driver

> +static int ipq_mdio_reset(struct mii_bus *bus)
> +{
> +	struct ipq4019_mdio_data *priv = bus->priv;
> +	u32 val;
> +	int ret;
> +
> +	/* To indicate CMN_PLL that ethernet_ldo has been ready if platform resource 1
> +	 * is specified in the device tree.
> +	 * */
> +	if (!IS_ERR(priv->eth_ldo_rdy)) {
> +		val = readl(priv->eth_ldo_rdy);
> +		val |= BIT(0);
> +		writel(val, priv->eth_ldo_rdy);
> +		fsleep(IPQ_PHY_SET_DELAY_US);
> +	}
> +
> +	/* Configure MDIO clock source frequency if clock is specified in the device tree */
> +	if (!IS_ERR_OR_NULL(priv->mdio_clk)) {
> +		ret = clk_set_rate(priv->mdio_clk, IPQ_MDIO_CLK_RATE);
> +		if (ret)
> +			return ret;
> +
> +		ret = clk_prepare_enable(priv->mdio_clk);
> +		if (ret)
> +			return ret;
> +	}

These !IS_ERR() are pretty ugly. So

> @@ -182,14 +221,22 @@ static int ipq4019_mdio_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	priv = bus->priv;
> +	priv->eth_ldo_rdy = IOMEM_ERR_PTR(-EINVAL);
>  
>  	priv->membase = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(priv->membase))
>  		return PTR_ERR(priv->membase);
>  
> +	priv->mdio_clk = devm_clk_get_optional(&pdev->dev, "gcc_mdio_ahb_clk");

If this returns an error, it is a real error. You should not ignore
it. Fail the probe returning the error. That then means when the reset
function is called priv->mdio_clk contains either a clock, or NULL,
which the clk API is happy to take. No need for an if.


> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	if (res)
> +		priv->eth_ldo_rdy = devm_ioremap_resource(&pdev->dev, res);

platform_get_resource() returns a pointer or NULL. There is no error
code. So

> +	if (!IS_ERR(priv->eth_ldo_rdy)) {

is actually wrong, should simply become

> +	if (priv->eth_ldo_rdy) {

  Andrew