generic: interface mode switch for RTL8221B PHY

Add dynamic interface mode update for the rtl8221 phy to match various
wire speeds. 10M/100M/1000M use SGMII, 2500M uses 2500Base-X.

Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/target/linux/generic/pending-5.15/722-net-phy-realtek-support-switching-between-SGMII-and-.patch b/target/linux/generic/pending-5.15/722-net-phy-realtek-support-switching-between-SGMII-and-.patch
new file mode 100644
index 0000000000..f4e87f52de
--- /dev/null
+++ b/target/linux/generic/pending-5.15/722-net-phy-realtek-support-switching-between-SGMII-and-.patch
@@ -0,0 +1,61 @@
+From 312753d0aadba0f58841ae513b80fdbabc887523 Mon Sep 17 00:00:00 2001
+From: Chukun Pan <amadeus@jmu.edu.cn>
+Date: Wed, 8 Feb 2023 16:32:18 +0800
+Subject: [PATCH] net: phy: realtek: support switching between SGMII and
+ 2500BASE-X for RTL822x series
+
+After commit ace6aba ("net: phy: realtek: rtl8221: allow to configure
+SERDES mode"), the rtl8221 phy can work in SGMII and 2500base-x modes
+respectively. So add interface automatic switching for rtl8221 phy to
+match various wire speeds.
+
+Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
+---
+ drivers/net/phy/realtek.c | 26 ++++++++++++++++++++++++--
+ 1 file changed, 24 insertions(+), 2 deletions(-)
+
+--- a/drivers/net/phy/realtek.c
++++ b/drivers/net/phy/realtek.c
+@@ -676,6 +676,25 @@ static int rtl822x_config_aneg(struct ph
+ 	return __genphy_config_aneg(phydev, ret);
+ }
+ 
++static void rtl822x_update_interface(struct phy_device *phydev)
++{
++	/* Automatically switch SERDES interface between
++	 * SGMII and 2500-BaseX according to speed.
++	 */
++	switch (phydev->speed) {
++	case SPEED_2500:
++		phydev->interface = PHY_INTERFACE_MODE_2500BASEX;
++		break;
++	case SPEED_1000:
++	case SPEED_100:
++	case SPEED_10:
++		phydev->interface = PHY_INTERFACE_MODE_SGMII;
++		break;
++	default:
++		break;
++	}
++}
++
+ static int rtl822x_read_status(struct phy_device *phydev)
+ {
+ 	int ret;
+@@ -694,11 +713,14 @@ static int rtl822x_read_status(struct ph
+ 			phydev->lp_advertising, lpadv & RTL_LPADV_2500FULL);
+ 	}
+ 
+-	ret = genphy_read_status(phydev);
++	ret = rtlgen_read_status(phydev);
+ 	if (ret < 0)
+ 		return ret;
+ 
+-	return rtlgen_get_speed(phydev);
++	if (phydev->link)
++		rtl822x_update_interface(phydev);
++
++	return 0;
+ }
+ 
+ static bool rtlgen_supports_2_5gbps(struct phy_device *phydev)