net: fec: fix MAC internal delay doesn't work

This patch intends to fix MAC internal delay doesn't work, due to use
of_property_read_u32() incorrectly, and improve this feature a bit:
1) check the delay value if valid, only program register when it's 2000ps.
2) only enable "enet_2x_txclk" clock when require MAC internal delay.

Fixes: fc53945 ("net: fec: add MAC internal delayed clock feature support")
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Link: https://lore.kernel.org/r/20210803052424.19008-1-qiangqing.zhang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/freescale/fec_main.c

@@ -2042,6 +2042,34 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
 	return ret;
 }
 
+static int fec_enet_parse_rgmii_delay(struct fec_enet_private *fep,
+				      struct device_node *np)
+{
+	u32 rgmii_tx_delay, rgmii_rx_delay;
+
+	/* For rgmii tx internal delay, valid values are 0ps and 2000ps */
+	if (!of_property_read_u32(np, "tx-internal-delay-ps", &rgmii_tx_delay)) {
+		if (rgmii_tx_delay != 0 && rgmii_tx_delay != 2000) {
+			dev_err(&fep->pdev->dev, "The only allowed RGMII TX delay values are: 0ps, 2000ps");
+			return -EINVAL;
+		} else if (rgmii_tx_delay == 2000) {
+			fep->rgmii_txc_dly = true;
+		}
+	}
+
+	/* For rgmii rx internal delay, valid values are 0ps and 2000ps */
+	if (!of_property_read_u32(np, "rx-internal-delay-ps", &rgmii_rx_delay)) {
+		if (rgmii_rx_delay != 0 && rgmii_rx_delay != 2000) {
+			dev_err(&fep->pdev->dev, "The only allowed RGMII RX delay values are: 0ps, 2000ps");
+			return -EINVAL;
+		} else if (rgmii_rx_delay == 2000) {
+			fep->rgmii_rxc_dly = true;
+		}
+	}
+
+	return 0;
+}
+
 static int fec_enet_mii_probe(struct net_device *ndev)
 {
 	struct fec_enet_private *fep = netdev_priv(ndev);
@@ -3719,7 +3747,6 @@ fec_probe(struct platform_device *pdev)
 	char irq_name[8];
 	int irq_cnt;
 	struct fec_devinfo *dev_info;
-	u32 rgmii_delay;
 
 	fec_enet_get_queue_num(pdev, &num_tx_qs, &num_rx_qs);
 
@@ -3777,12 +3804,6 @@ fec_probe(struct platform_device *pdev)
 	if (ret)
 		goto failed_stop_mode;
 
-	/* For rgmii internal delay, valid values are 0ps and 2000ps */
-	if (of_property_read_u32(np, "tx-internal-delay-ps", &rgmii_delay))
-		fep->rgmii_txc_dly = true;
-	if (of_property_read_u32(np, "rx-internal-delay-ps", &rgmii_delay))
-		fep->rgmii_rxc_dly = true;
-
 	phy_node = of_parse_phandle(np, "phy-handle", 0);
 	if (!phy_node && of_phy_is_fixed_link(np)) {
 		ret = of_phy_register_fixed_link(np);
@@ -3806,6 +3827,10 @@ fec_probe(struct platform_device *pdev)
 		fep->phy_interface = interface;
 	}
 
+	ret = fec_enet_parse_rgmii_delay(fep, np);
+	if (ret)
+		goto failed_rgmii_delay;
+
 	fep->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(fep->clk_ipg)) {
 		ret = PTR_ERR(fep->clk_ipg);
@@ -3835,9 +3860,11 @@ fec_probe(struct platform_device *pdev)
 	fep->clk_ref_rate = clk_get_rate(fep->clk_ref);
 
 	/* clk_2x_txclk is optional, depends on board */
-	fep->clk_2x_txclk = devm_clk_get(&pdev->dev, "enet_2x_txclk");
-	if (IS_ERR(fep->clk_2x_txclk))
-		fep->clk_2x_txclk = NULL;
+	if (fep->rgmii_txc_dly || fep->rgmii_rxc_dly) {
+		fep->clk_2x_txclk = devm_clk_get(&pdev->dev, "enet_2x_txclk");
+		if (IS_ERR(fep->clk_2x_txclk))
+			fep->clk_2x_txclk = NULL;
+	}
 
 	fep->bufdesc_ex = fep->quirks & FEC_QUIRK_HAS_BUFDESC_EX;
 	fep->clk_ptp = devm_clk_get(&pdev->dev, "ptp");
@@ -3955,6 +3982,7 @@ fec_probe(struct platform_device *pdev)
 failed_clk_ipg:
 	fec_enet_clk_enable(ndev, false);
 failed_clk:
+failed_rgmii_delay:
 	if (of_phy_is_fixed_link(np))
 		of_phy_deregister_fixed_link(np);
 	of_node_put(phy_node);