Subject: Re: [Patch net-next v14 11/13] net: dsa: microchip: lan937x: add phylink_mac_link_up support

From: "Russell King (Oracle)" <[email-masked]>
Date: Thu, 30 Jun 2022 12:42:26 +0100

On Thu, Jun 30, 2022 at 03:50:39PM +0530, Arun Ramadoss wrote:
> +static void lan937x_config_gbit(struct ksz_device *dev, bool gbit, u8 *data)
> +{
> +	if (gbit)
> +		*data &= ~PORT_MII_NOT_1GBIT;
> +	else
> +		*data |= PORT_MII_NOT_1GBIT;
> +}
> +
> +static void lan937x_config_interface(struct ksz_device *dev, int port,
> +				     int speed, int duplex,
> +				     bool tx_pause, bool rx_pause)
> +{
> +	u8 xmii_ctrl0, xmii_ctrl1;
> +
> +	ksz_pread8(dev, port, REG_PORT_XMII_CTRL_0, &xmii_ctrl0);
> +	ksz_pread8(dev, port, REG_PORT_XMII_CTRL_1, &xmii_ctrl1);
> +
> +	switch (speed) {
> +	case SPEED_1000:
> +		lan937x_config_gbit(dev, true, &xmii_ctrl1);
> +		break;
> +	case SPEED_100:
> +		lan937x_config_gbit(dev, false, &xmii_ctrl1);
> +		xmii_ctrl0 |= PORT_MII_100MBIT;
> +		break;
> +	case SPEED_10:
> +		lan937x_config_gbit(dev, false, &xmii_ctrl1);
> +		xmii_ctrl0 &= ~PORT_MII_100MBIT;
> +		break;
> +	default:
> +		dev_err(dev->dev, "Unsupported speed on port %d: %d\n",
> +			port, speed);
> +		return;
> +	}

Isn't this:

	if (speed == SPEED_1000)
		xmii_ctrl1 &= ~PORT_MII_NOT_1GBIT;
	else
		xmii_ctrl1 |= PORT_MII_NOT_1GBIT;

	if (speed == SPEED_100)
		xmii_ctrl0 |= PORT_MII_100MBIT;
	else
		xmii_ctrl0 &= ~PORT_MII_100MBIT;

There isn't much need to validate that "speed" is correct, you've
already told phylink that you only support 1G, 100M and 10M so you're
not going to get called with anything except one of those.

> +
> +	if (duplex)
> +		xmii_ctrl0 |= PORT_MII_FULL_DUPLEX;
> +	else
> +		xmii_ctrl0 &= ~PORT_MII_FULL_DUPLEX;
> +
> +	if (tx_pause)
> +		xmii_ctrl0 |= PORT_MII_TX_FLOW_CTRL;
> +	else
> +		xmii_ctrl1 &= ~PORT_MII_TX_FLOW_CTRL;

It seems weird to set a bit in one register and clear it in a different
register. I suspect you mean xmii_ctrl0 here.

> +
> +	if (rx_pause)
> +		xmii_ctrl0 |= PORT_MII_RX_FLOW_CTRL;
> +	else
> +		xmii_ctrl0 &= ~PORT_MII_RX_FLOW_CTRL;
> +
> +	ksz_pwrite8(dev, port, REG_PORT_XMII_CTRL_0, xmii_ctrl0);
> +	ksz_pwrite8(dev, port, REG_PORT_XMII_CTRL_1, xmii_ctrl1);
> +}
> +

Thanks!

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