net: stmmac: dwmac-meson8b: only configure the clocks in RGMII mode

Neither the m25_div_clk nor the m250_div_clk or m250_mux_clk are used in
RMII mode. The m25_div_clk output is routed to the RGMII PHY's "RGMII
clock".
This means that we don't need to configure the clocks in RMII mode. The
driver however did this - with no effect since the clocks are not routed
to the PHY in RMII mode.

While here also rename meson8b_init_clk to meson8b_init_rgmii_tx_clk to
make it easier to understand the code.

Fixes: 566e8251 ("net: stmmac: add a glue driver for the Amlogic Meson 8b / GXBB DWMAC")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -81,7 +81,7 @@ static void meson8b_dwmac_mask_bits(struct meson8b_dwmac *dwmac, u32 reg,
 	writel(data, dwmac->regs + reg);
 }
 
-static int meson8b_init_clk(struct meson8b_dwmac *dwmac)
+static int meson8b_init_rgmii_tx_clk(struct meson8b_dwmac *dwmac)
 {
 	struct clk_init_data init;
 	int i, ret;
@@ -176,7 +176,6 @@ static int meson8b_init_clk(struct meson8b_dwmac *dwmac)
 static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
 {
 	int ret;
-	unsigned long clk_rate;
 	u8 tx_dly_val = 0;
 
 	switch (dwmac->phy_mode) {
@@ -191,9 +190,6 @@ static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
 
 	case PHY_INTERFACE_MODE_RGMII_ID:
 	case PHY_INTERFACE_MODE_RGMII_TXID:
-		/* Generate a 25MHz clock for the PHY */
-		clk_rate = 25 * 1000 * 1000;
-
 		/* enable RGMII mode */
 		meson8b_dwmac_mask_bits(dwmac, PRG_ETH0, PRG_ETH0_RGMII_MODE,
 					PRG_ETH0_RGMII_MODE);
@@ -204,12 +200,24 @@ static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
 
 		meson8b_dwmac_mask_bits(dwmac, PRG_ETH0, PRG_ETH0_TXDLY_MASK,
 					tx_dly_val << PRG_ETH0_TXDLY_SHIFT);
+
+		ret = clk_prepare_enable(dwmac->m25_div_clk);
+		if (ret) {
+			dev_err(&dwmac->pdev->dev, "failed to enable the PHY clock\n");
+			return ret;
+		}
+
+		/* Generate the 25MHz RGMII clock for the PHY */
+		ret = clk_set_rate(dwmac->m25_div_clk, 25 * 1000 * 1000);
+		if (ret) {
+			clk_disable_unprepare(dwmac->m25_div_clk);
+
+			dev_err(&dwmac->pdev->dev, "failed to set PHY clock\n");
+			return ret;
+		}
 		break;
 
 	case PHY_INTERFACE_MODE_RMII:
-		/* Use the rate of the mux clock for the internal RMII PHY */
-		clk_rate = clk_get_rate(dwmac->m250_mux_clk);
-
 		/* disable RGMII mode -> enables RMII mode */
 		meson8b_dwmac_mask_bits(dwmac, PRG_ETH0, PRG_ETH0_RGMII_MODE,
 					0);
@@ -231,20 +239,6 @@ static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
 		return -EINVAL;
 	}
 
-	ret = clk_prepare_enable(dwmac->m25_div_clk);
-	if (ret) {
-		dev_err(&dwmac->pdev->dev, "failed to enable the PHY clock\n");
-		return ret;
-	}
-
-	ret = clk_set_rate(dwmac->m25_div_clk, clk_rate);
-	if (ret) {
-		clk_disable_unprepare(dwmac->m25_div_clk);
-
-		dev_err(&dwmac->pdev->dev, "failed to set PHY clock\n");
-		return ret;
-	}
-
 	/* enable TX_CLK and PHY_REF_CLK generator */
 	meson8b_dwmac_mask_bits(dwmac, PRG_ETH0, PRG_ETH0_TX_AND_PHY_REF_CLK,
 				PRG_ETH0_TX_AND_PHY_REF_CLK);
@@ -294,7 +288,7 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
 				 &dwmac->tx_delay_ns))
 		dwmac->tx_delay_ns = 2;
 
-	ret = meson8b_init_clk(dwmac);
+	ret = meson8b_init_rgmii_tx_clk(dwmac);
 	if (ret)
 		goto err_remove_config_dt;
 
@@ -311,7 +305,8 @@ static int meson8b_dwmac_probe(struct platform_device *pdev)
 	return 0;
 
 err_clk_disable:
-	clk_disable_unprepare(dwmac->m25_div_clk);
+	if (phy_interface_mode_is_rgmii(dwmac->phy_mode))
+		clk_disable_unprepare(dwmac->m25_div_clk);
 err_remove_config_dt:
 	stmmac_remove_config_dt(pdev, plat_dat);
 
@@ -322,7 +317,8 @@ static int meson8b_dwmac_remove(struct platform_device *pdev)
 {
 	struct meson8b_dwmac *dwmac = get_stmmac_bsp_priv(&pdev->dev);
 
-	clk_disable_unprepare(dwmac->m25_div_clk);
+	if (phy_interface_mode_is_rgmii(dwmac->phy_mode))
+		clk_disable_unprepare(dwmac->m25_div_clk);
 
 	return stmmac_pltfr_remove(pdev);
 }