netdev - Re: [PATCH 1/3] net: mdio-ipq4019: Add mdio reset function

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Date:   Thu, 29 Jul 2021 15:26:54 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Luo Jie <luoj@...eaurora.org>
Cc:     hkallweit1@...il.com, davem@...emloft.net, kuba@...nel.org,
        p.zabel@...gutronix.de, agross@...nel.org,
        bjorn.andersson@...aro.org, robh+dt@...nel.org,
        robert.marko@...tura.hr, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, sricharan@...eaurora.org
Subject: Re: [PATCH 1/3] net: mdio-ipq4019: Add mdio reset function

Hi Luo

For a patchset, netdev wants to see a patch 0/X which describes the
big picture. What is the patchset as a whole doing.

> +static int ipq_mdio_reset(struct mii_bus *bus)
> +{
> +	struct ipq4019_mdio_data *priv = bus->priv;
> +	struct device *dev = bus->parent;
> +	struct gpio_desc *reset_gpio;
> +	u32 val;
> +	int i, ret;
> +
> +	/* To indicate CMN_PLL that ethernet_ldo has been ready if needed */
> +	if (!IS_ERR(priv->eth_ldo_rdy)) {
> +		val = readl(priv->eth_ldo_rdy);
> +		val |= BIT(0);
> +		writel(val, priv->eth_ldo_rdy);
> +		fsleep(QCA_PHY_SET_DELAY_US);
> +	}
> +
> +	/* Reset GEPHY if need */
> +	if (!IS_ERR(priv->reset_ctrl)) {
> +		reset_control_assert(priv->reset_ctrl);
> +		fsleep(QCA_PHY_SET_DELAY_US);
> +		reset_control_deassert(priv->reset_ctrl);
> +		fsleep(QCA_PHY_SET_DELAY_US);
> +	}

What exactly is being reset here? Which is GEPHY?

The MDIO bus master driver should not be touching any Ethernet
PHYs. All it provides is a bus, nothing more.

> +
> +	/* Configure MDIO clock frequency */
> +	if (!IS_ERR(priv->mdio_clk)) {
> +		ret = clk_set_rate(priv->mdio_clk, QCA_MDIO_CLK_RATE);
> +		if (ret)
> +			return ret;
> +
> +		ret = clk_prepare_enable(priv->mdio_clk);
> +		if (ret)
> +			return ret;
> +	}

> +
> +	/* Reset PHYs by gpio pins */
> +	for (i = 0; i < gpiod_count(dev, "phy-reset"); i++) {
> +		reset_gpio = gpiod_get_index_optional(dev, "phy-reset", i, GPIOD_OUT_HIGH);
> +		if (IS_ERR(reset_gpio))
> +			continue;
> +		gpiod_set_value_cansleep(reset_gpio, 0);
> +		fsleep(QCA_PHY_SET_DELAY_US);
> +		gpiod_set_value_cansleep(reset_gpio, 1);
> +		fsleep(QCA_PHY_SET_DELAY_US);
> +		gpiod_put(reset_gpio);
> +	}

No, there is common code in phylib to do that.

>  static int ipq4019_mdio_probe(struct platform_device *pdev)
>  {
>  	struct ipq4019_mdio_data *priv;
>  	struct mii_bus *bus;
> +	struct resource *res;
>  	int ret;
>  
>  	bus = devm_mdiobus_alloc_size(&pdev->dev, sizeof(*priv));
> @@ -182,14 +244,23 @@ 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);
>  
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	if (res)
> +		priv->eth_ldo_rdy = devm_ioremap_resource(&pdev->dev, res);
> +
> +	priv->reset_ctrl = devm_reset_control_get_exclusive(&pdev->dev, "gephy_mdc_rst");
> +	priv->mdio_clk = devm_clk_get(&pdev->dev, "gcc_mdio_ahb_clk");

You probably want to use devm_clk_get_optional().

    Andrew