[RFC PATCH net] net: dsa: mt7530: move PLL setup out of port 6 pad configuration

[arinc9.unal at gmail.com]

From: Arınç ÜNAL <arinc.unal at arinc9.com>

Move the PLL setup of the MT7530 switch out of the pad configuration of
port 6 to mt7530_setup, after reset.

This fixes the improper initialisation of the switch when only port 5 is
used as a CPU port.

Add supported phy modes of port 5 on the PLL setup.

Remove now incorrect comment regarding P5 as GMAC5.

Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Fixes: 38f790a80560 ("net: dsa: mt7530: Add support for port 5")
Signed-off-by: Arınç ÜNAL <arinc.unal at arinc9.com>
---

I'm trying to mimic this change by Alexander [0] for the MT7530 switch.
This is already the case for MT7530 and MT7531 on the MediaTek ethernet
driver on U-Boot [1] [2].

[0] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=42bc4fafe359ed6b73602b7a2dba0dd99588f8ce
[1] https://github.com/u-boot/u-boot/blob/a94ab561e2f49a80d8579930e840b810ab1a1330/drivers/net/mtk_eth.c#L729
[2] https://github.com/u-boot/u-boot/blob/a94ab561e2f49a80d8579930e840b810ab1a1330/drivers/net/mtk_eth.c#L903

There are some parts I couldn't figure out myself with my limited C
knowledge. I've pointed them out on the code. Vladimir, could you help?

There is a lot of code which is only needed for port 6 or trgmii on port 6,
but runs whether port 6 or trgmii is used or not. For now, the best I can
do is to fix port 5 so it works without port 6 being used.

The U-Boot driver seems to be much more organised so it could be taken as
a reference to sort out this DSA driver further.

Also, now that the pad setup for mt7530 is also moved somewhere else, can
we completely get rid of @pad_setup?

Arınç

---
 drivers/net/dsa/mt7530.c | 46 +++++++++++++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 0e99de26d159..fb20ce4f443e 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -395,9 +395,8 @@ mt7530_fdb_write(struct mt7530_priv *priv, u16 vid,
 
 /* Setup TX circuit including relevant PAD and driving */
 static int
-mt7530_pad_clk_setup(struct dsa_switch *ds, phy_interface_t interface)
+mt7530_pad_clk_setup(struct mt7530_priv *priv, phy_interface_t interface)
 {
-	struct mt7530_priv *priv = ds->priv;
 	u32 ncpo1, ssc_delta, trgint, i, xtal;
 
 	xtal = mt7530_read(priv, MT7530_MHWTRAP) & HWTRAP_XTAL_MASK;
@@ -409,9 +408,32 @@ mt7530_pad_clk_setup(struct dsa_switch *ds, phy_interface_t interface)
 		return -EINVAL;
 	}
 
+	/* Is setting trgint to 0 really needed for the !trgint check? */
+	trgint = 0;
+
+	/* FIXME: run this switch if p5 is defined on the devicetree */
+	/* and change interface to the phy-mode of port 5 */
+	switch (interface) {
+	case PHY_INTERFACE_MODE_GMII:
+		/* PLL frequency: 125MHz */
+		ncpo1 = 0x0c80;
+		break;
+	case PHY_INTERFACE_MODE_MII:
+		break;
+	case PHY_INTERFACE_MODE_RGMII:
+		/* PLL frequency: 125MHz */
+		ncpo1 = 0x0c80;
+		break;
+	default:
+		dev_err(priv->dev, "xMII interface %d not supported\n",
+			interface);
+		return -EINVAL;
+	}
+
+	/* FIXME: run this switch if p6 is defined on the devicetree */
+	/* and change interface to the phy-mode of port 6 */
 	switch (interface) {
 	case PHY_INTERFACE_MODE_RGMII:
-		trgint = 0;
 		/* PLL frequency: 125MHz */
 		ncpo1 = 0x0c80;
 		break;
@@ -2172,7 +2194,11 @@ mt7530_setup(struct dsa_switch *ds)
 		     SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |
 		     SYS_CTRL_REG_RST);
 
-	/* Enable Port 6 only; P5 as GMAC5 which currently is not supported */
+	/* Setup switch core pll */
+	/* FIXME: feed the phy-mode of port 5 and 6, if the ports are defined on the devicetree */
+	mt7530_pad_clk_setup(priv, interface);
+
+	/* Enable Port 6 */
 	val = mt7530_read(priv, MT7530_MHWTRAP);
 	val &= ~MHWTRAP_P6_DIS & ~MHWTRAP_PHY_ACCESS;
 	val |= MHWTRAP_MANUAL;
@@ -2491,11 +2517,9 @@ static void mt7531_mac_port_get_caps(struct dsa_switch *ds, int port,
 }
 
 static int
-mt753x_pad_setup(struct dsa_switch *ds, const struct phylink_link_state *state)
+mt7530_pad_setup(struct dsa_switch *ds, phy_interface_t interface)
 {
-	struct mt7530_priv *priv = ds->priv;
-
-	return priv->info->pad_setup(ds, state->interface);
+	return 0;
 }
 
 static int
@@ -2769,8 +2793,6 @@ mt753x_phylink_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
 		if (priv->p6_interface == state->interface)
 			break;
 
-		mt753x_pad_setup(ds, state);
-
 		if (mt753x_mac_config(ds, port, mode, state) < 0)
 			goto unsupported;
 
@@ -3187,7 +3209,7 @@ static const struct mt753x_info mt753x_table[] = {
 		.phy_write_c22 = mt7530_phy_write_c22,
 		.phy_read_c45 = mt7530_phy_read_c45,
 		.phy_write_c45 = mt7530_phy_write_c45,
-		.pad_setup = mt7530_pad_clk_setup,
+		.pad_setup = mt7530_pad_setup,
 		.mac_port_get_caps = mt7530_mac_port_get_caps,
 		.mac_port_config = mt7530_mac_config,
 	},
@@ -3199,7 +3221,7 @@ static const struct mt753x_info mt753x_table[] = {
 		.phy_write_c22 = mt7530_phy_write_c22,
 		.phy_read_c45 = mt7530_phy_read_c45,
 		.phy_write_c45 = mt7530_phy_write_c45,
-		.pad_setup = mt7530_pad_clk_setup,
+		.pad_setup = mt7530_pad_setup,
 		.mac_port_get_caps = mt7530_mac_port_get_caps,
 		.mac_port_config = mt7530_mac_config,
 	},
-- 
2.37.2