[PATCH v5 1/2] stmmac: dwmac-mediatek: enable 2ns delay only for special cases

[Biao Huang <biao.huang@mediatek.com>]

In current driver, MAC will always enable 2ns delay in RGMII mode,
but that will lead to transmission failures for "rgmii-id"/"rgmii-txid"
cases.

Modify the implementation of fix_mac_speed() to ensure the 2ns delay
will only take effect for "rgmii-rxid"/"rgmii" cases, then user can
choose phy-mode freely.

Fixes: f2d356a6ab71 ("stmmac: dwmac-mediatek: add support for mt8195")
Signed-off-by: Biao Huang <biao.huang@mediatek.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
index d42e1afb6521..cde4fb81d596 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
@@ -447,7 +447,9 @@ static void mt8195_fix_mac_speed(void *priv, unsigned int speed)
 {
 	struct mediatek_dwmac_plat_data *priv_plat = priv;
 
-	if ((phy_interface_mode_is_rgmii(priv_plat->phy_mode))) {
+	switch (priv_plat->phy_mode) {
+	case PHY_INTERFACE_MODE_RGMII:
+	case PHY_INTERFACE_MODE_RGMII_RXID:
 		/* prefer 2ns fixed delay which is controlled by TXC_PHASE_CTRL,
 		 * when link speed is 1Gbps with RGMII interface,
 		 * Fall back to delay macro circuit for 10/100Mbps link speed.
@@ -462,6 +464,9 @@ static void mt8195_fix_mac_speed(void *priv, unsigned int speed)
 					   MT8195_RGMII_TXC_PHASE_CTRL);
 		else
 			mt8195_set_delay(priv_plat);
+		break;
+	default:
+		break;
 	}
 }
 
-- 
2.25.1