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From:   Vladimir Oltean <vladimir.oltean@nxp.com>
To:     netdev@vger.kernel.org
Cc:     Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        Harini Katakam <harini.katakam@amd.com>
Subject: [PATCH v2 net-next] net: phy: mscc: fix packet loss due to RGMII delays
Date:   Tue, 27 Jun 2023 16:42:35 +0300
Message-Id: <20230627134235.3453358-1-vladimir.oltean@nxp.com>
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Two deadly typos break RX and TX traffic on the VSC8502 PHY using RGMII
if phy-mode = "rgmii-id" or "rgmii-txid", and no "tx-internal-delay-ps"
override exists. The negative error code from phy_get_internal_delay()
does not get overridden with the delay deduced from the phy-mode, and
later gets committed to hardware. Also, the rx_delay gets overridden by
what should have been the tx_delay.

Fixes: dbb050d2bfc8 ("phy: mscc: Add support for RGMII delay configuration")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Harini Katakam <harini.katakam@amd.com>
---
v1->v2: resend to net-next

 drivers/net/phy/mscc/mscc_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/mscc/mscc_main.c b/drivers/net/phy/mscc/mscc_main.c
index 669a4a7a28ce..4171f01d34e5 100644
--- a/drivers/net/phy/mscc/mscc_main.c
+++ b/drivers/net/phy/mscc/mscc_main.c
@@ -563,9 +563,9 @@ static int vsc85xx_update_rgmii_cntl(struct phy_device *phydev, u32 rgmii_cntl,
 	if (tx_delay < 0) {
 		if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
 		    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
-			rx_delay = RGMII_CLK_DELAY_2_0_NS;
+			tx_delay = RGMII_CLK_DELAY_2_0_NS;
 		else
-			rx_delay = RGMII_CLK_DELAY_0_2_NS;
+			tx_delay = RGMII_CLK_DELAY_0_2_NS;
 	}
 
 	reg_val |= rx_delay << rgmii_rx_delay_pos;
-- 
2.34.1