netdev - Re: [PATCH v4 1/5] net: mdio: ipq4019: move eth_ldo

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Date: Thu, 28 Dec 2023 10:49:51 +0100
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Luo Jie <quic_luoj@...cinc.com>, agross@...nel.org, andersson@...nel.org,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
 conor+dt@...nel.org, andrew@...n.ch, hkallweit1@...il.com,
 linux@...linux.org.uk, robert.marko@...tura.hr
Cc: linux-arm-msm@...r.kernel.org, netdev@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 quic_srichara@...cinc.com
Subject: Re: [PATCH v4 1/5] net: mdio: ipq4019: move eth_ldo_rdy before MDIO
 bus register

On 25.12.2023 09:44, Luo Jie wrote:
> The ethernet LDO provides the clock for the ethernet PHY that
> is connected with PCS, each LDO enables the clock output to
> each PCS, after the clock output enablement, the PHY GPIO reset
> can take effect.
> 
> For the PHY taking the MDIO bus level GPIO reset, the ethernet
> LDO should be enabled before the MDIO bus register.
> 
> For example, the qca8084 PHY takes the MDIO bus level GPIO
> reset for quad PHYs, there is another reason for qca8084 PHY
> using MDIO bus level GPIO reset instead of PHY level GPIO
> reset as below.
> 
> The work sequence of qca8084:
> 1. enable ethernet LDO.
> 2. GPIO reset on quad PHYs.
> 3. register clock provider based on MDIO device of qca8084.
> 4. PHY probe function called for initializing common clocks.
> 5. PHY capabilities acquirement.
> 
> If qca8084 takes PHY level GPIO reset in the step 4, the clock
> provider of qca8084 can't be registered correctly, since the
> clock parent(reading the current qca8084 hardware registers in
> step 3) of the registered clocks is deserted after GPIO reset.
> 
> There are two PCS(UNIPHY) supported in SOC side on ipq5332,
> and three PCS(UNIPHY) supported on ipq9574.
> 
> Signed-off-by: Luo Jie <quic_luoj@...cinc.com>
> ---
>  drivers/net/mdio/mdio-ipq4019.c | 51 +++++++++++++++++++++------------
>  1 file changed, 32 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/net/mdio/mdio-ipq4019.c b/drivers/net/mdio/mdio-ipq4019.c
> index abd8b508ec16..5273864fabb3 100644
> --- a/drivers/net/mdio/mdio-ipq4019.c
> +++ b/drivers/net/mdio/mdio-ipq4019.c
> @@ -37,9 +37,12 @@
>  
>  #define IPQ_PHY_SET_DELAY_US	100000
>  
> +/* Maximum SOC PCS(uniphy) number on IPQ platform */
> +#define ETH_LDO_RDY_CNT				3
> +
>  struct ipq4019_mdio_data {
> -	void __iomem	*membase;
> -	void __iomem *eth_ldo_rdy;
> +	void __iomem *membase;
> +	void __iomem *eth_ldo_rdy[ETH_LDO_RDY_CNT];
>  	struct clk *mdio_clk;
>  };
>  
> @@ -206,19 +209,8 @@ static int ipq4019_mdio_write_c22(struct mii_bus *bus, int mii_id, int regnum,
>  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 (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 */
>  	ret = clk_set_rate(priv->mdio_clk, IPQ_MDIO_CLK_RATE);
>  	if (ret)
> @@ -236,7 +228,7 @@ static int ipq4019_mdio_probe(struct platform_device *pdev)
>  	struct ipq4019_mdio_data *priv;
>  	struct mii_bus *bus;
>  	struct resource *res;
> -	int ret;
> +	int ret, index;
>  
>  	bus = devm_mdiobus_alloc_size(&pdev->dev, sizeof(*priv));
>  	if (!bus)
> @@ -252,11 +244,32 @@ static int ipq4019_mdio_probe(struct platform_device *pdev)
>  	if (IS_ERR(priv->mdio_clk))
>  		return PTR_ERR(priv->mdio_clk);
>  
> -	/* The platform resource is provided on the chipset IPQ5018 */
> -	/* This resource is optional */
> -	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> -	if (res)
> -		priv->eth_ldo_rdy = devm_ioremap_resource(&pdev->dev, res);
> +	/* These platform resources are provided on the chipset IPQ5018 or
> +	 * IPQ5332.
> +	 */
> +	/* This resource are optional */
> +	for (index = 0; index < ETH_LDO_RDY_CNT; index++) {
> +		res = platform_get_resource(pdev, IORESOURCE_MEM, index + 1);
> +		if (res) {
if (!res)
	break

> +			priv->eth_ldo_rdy[index] = devm_ioremap(&pdev->dev,
> +								res->start,
> +								resource_size(res));
> +
> +			/* The ethernet LDO enable is necessary to reset PHY
> +			 * by GPIO, some PHY(such as qca8084) GPIO reset uses
> +			 * the MDIO level reset, so this function should be
> +			 * called before the MDIO bus register.
> +			 */
> +			if (priv->eth_ldo_rdy[index]) {
> +				u32 val;
> +
> +				val = readl(priv->eth_ldo_rdy[index]);
> +				val |= BIT(0);
> +				writel(val, priv->eth_ldo_rdy[index]);
> +				fsleep(IPQ_PHY_SET_DELAY_US);
fsleep should only be used when the argument is variable

Konrad