net: stmmac: dwmac-meson8b: move RGMII delays into a separate function

Newer SoCs starting with the Amlogic Meson G12A have more a precise
RGMII RX delay configuration register. This means more complexity in the
code. Extract the existing RGMII delay configuration code into a
separate function to make it easier to read/understand even when adding
more logic in the future.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c

@@ -268,7 +268,7 @@ static int meson8b_devm_clk_prepare_enable(struct meson8b_dwmac *dwmac,
 	return 0;
 }
 
-static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
+static int meson8b_init_rgmii_delays(struct meson8b_dwmac *dwmac)
 {
 	u32 tx_dly_config, rx_dly_config, delay_config;
 	int ret;
@@ -323,6 +323,13 @@ static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
 				PRG_ETH0_ADJ_DELAY | PRG_ETH0_ADJ_SKEW,
 				delay_config);
 
+	return 0;
+}
+
+static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
+{
+	int ret;
+
 	if (phy_interface_mode_is_rgmii(dwmac->phy_mode)) {
 		/* only relevant for RMII mode -> disable in RGMII mode */
 		meson8b_dwmac_mask_bits(dwmac, PRG_ETH0,
@@ -430,6 +437,10 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
 		goto err_remove_config_dt;
 	}
 
+	ret = meson8b_init_rgmii_delays(dwmac);
+	if (ret)
+		goto err_remove_config_dt;
+
 	ret = meson8b_init_rgmii_tx_clk(dwmac);
 	if (ret)
 		goto err_remove_config_dt;