On Tue, Aug 18, 2020 at 03:14:10PM +0800, Landen Chao wrote:

Add new support for MT7531:

MT7531 is the next generation of MT7530. It is also a 7-ports switch with
5 giga embedded phys, 2 cpu ports, and the same MAC logic of MT7530. Cpu
port 6 only supports SGMII interface. Cpu port 5 supports either RGMII
or SGMII in different HW sku. Due to SGMII interface support, pll, and
pad setting are different from MT7530. This patch adds different initial
setting, and SGMII phylink handlers of MT7531.

MT7531 SGMII interface can be configured in following mode:
- 'SGMII AN mode' with in-band negotiation capability
    which is compatible with PHY_INTERFACE_MODE_SGMII.
- 'SGMII force mode' without in-bnad negotiation

band

    which is compatible with 10B/8B encoding of
    PHY_INTERFACE_MODE_1000BASEX with fixed full-duplex and fixed pause.
- 2.5 times faster clocked 'SGMII force mode' without in-bnad negotiation

band

+static int mt7531_rgmii_setup(struct mt7530_priv *priv, u32 port,
+			      phy_interface_t interface)
+{
+	u32 val;
+
+	if (!mt7531_is_rgmii_port(priv, port)) {
+		dev_err(priv->dev, "RGMII mode is not available for port %d\n",
+			port);
+		return -EINVAL;
+	}
+
+	val = mt7530_read(priv, MT7531_CLKGEN_CTRL);
+	val |= GP_CLK_EN;
+	val &= ~GP_MODE_MASK;
+	val |= GP_MODE(MT7531_GP_MODE_RGMII);
+	val &= ~(TXCLK_NO_REVERSE | RXCLK_NO_DELAY);
+	switch (interface) {
+	case PHY_INTERFACE_MODE_RGMII:
+		val |= TXCLK_NO_REVERSE;
+		val |= RXCLK_NO_DELAY;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_RXID:
+		val |= TXCLK_NO_REVERSE;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_TXID:
+		val |= RXCLK_NO_DELAY;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_ID:
+		break;
+	default:
+		return -EINVAL;
+	}

You need to be careful here. If the MAC is doing the RGMII delays, you
need to ensure the PHY is not. What interface mode is passed to the
PHY?

	Andrew