phy: renesas: r8a779f0-ether-serdes: add new step added to latest datasheet

R-Car S4-8 datasheet Rev.1.20 describes some additional register
settings at the end of the initialization.

Signed-off-by: Michael Dege <michael.dege@renesas.com>
Link: https://lore.kernel.org/r/20250703-renesas-serdes-update-v4-2-1db5629cac2b@renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: mdege

drivers/phy/renesas/r8a779f0-ether-serdes.c

@@ -49,6 +49,13 @@ static void r8a779f0_eth_serdes_write32(void __iomem *addr, u32 offs, u32 bank,
 	iowrite32(data, addr + offs);
 }
 
+static u32 r8a779f0_eth_serdes_read32(void __iomem *addr, u32 offs,  u32 bank)
+{
+	iowrite32(bank, addr + R8A779F0_ETH_SERDES_BANK_SELECT);
+
+	return ioread32(addr + offs);
+}
+
 static int
 r8a779f0_eth_serdes_reg_wait(struct r8a779f0_eth_serdes_channel *channel,
 			     u32 offs, u32 bank, u32 mask, u32 expected)
@@ -319,6 +326,7 @@ static int r8a779f0_eth_serdes_hw_init_late(struct r8a779f0_eth_serdes_channel
 *channel)
 {
 	int ret;
+	u32 val;
 
 	ret = r8a779f0_eth_serdes_chan_setting(channel);
 	if (ret)
@@ -332,6 +340,26 @@ static int r8a779f0_eth_serdes_hw_init_late(struct r8a779f0_eth_serdes_channel
 
 	r8a779f0_eth_serdes_write32(channel->addr, 0x03d0, 0x380, 0x0000);
 
+	val = r8a779f0_eth_serdes_read32(channel->addr, 0x00c0, 0x180);
+	r8a779f0_eth_serdes_write32(channel->addr, 0x00c0, 0x180, val | BIT(8));
+	ret = r8a779f0_eth_serdes_reg_wait(channel, 0x0100, 0x180, BIT(0), 1);
+	if (ret)
+		return ret;
+	r8a779f0_eth_serdes_write32(channel->addr, 0x00c0, 0x180, val & ~BIT(8));
+	ret = r8a779f0_eth_serdes_reg_wait(channel, 0x0100, 0x180, BIT(0), 0);
+	if (ret)
+		return ret;
+
+	val = r8a779f0_eth_serdes_read32(channel->addr, 0x0144, 0x180);
+	r8a779f0_eth_serdes_write32(channel->addr, 0x0144, 0x180, val | BIT(4));
+	ret = r8a779f0_eth_serdes_reg_wait(channel, 0x0180, 0x180, BIT(0), 1);
+	if (ret)
+		return ret;
+	r8a779f0_eth_serdes_write32(channel->addr, 0x0144, 0x180, val & ~BIT(4));
+	ret = r8a779f0_eth_serdes_reg_wait(channel, 0x0180, 0x180, BIT(0), 0);
+	if (ret)
+		return ret;
+
 	return r8a779f0_eth_serdes_monitor_linkup(channel);
 }