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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Asmaa Mnebhi <asmaa@nvidia.com>,
        David Thompson <davthompson@nvidia.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 084/148] mlxbf_gige: clear MDIO gateway lock after read
Date:   Mon, 26 Sep 2022 12:11:58 +0200
Message-Id: <20220926100759.196718103@linuxfoundation.org>
In-Reply-To: <20220926100756.074519146@linuxfoundation.org>
References: <20220926100756.074519146@linuxfoundation.org>
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From: David Thompson <davthompson@nvidia.com>

[ Upstream commit 182447b12144b7be9b63a273d27c5a11bd54960a ]

The MDIO gateway (GW) lock in BlueField-2 GIGE logic is
set after read.  This patch adds logic to make sure the
lock is always cleared at the end of each MDIO transaction.

Fixes: f92e1869d74e ("Add Mellanox BlueField Gigabit Ethernet driver")
Reviewed-by: Asmaa Mnebhi <asmaa@nvidia.com>
Signed-off-by: David Thompson <davthompson@nvidia.com>
Link: https://lore.kernel.org/r/20220902164247.19862-1-davthompson@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_mdio.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_mdio.c b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_mdio.c
index f979ba7e5eff..caa4380ada13 100644
--- a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_mdio.c
+++ b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_mdio.c
@@ -178,6 +178,9 @@ static int mlxbf_gige_mdio_read(struct mii_bus *bus, int phy_add, int phy_reg)
 	/* Only return ad bits of the gw register */
 	ret &= MLXBF_GIGE_MDIO_GW_AD_MASK;
 
+	/* The MDIO lock is set on read. To release it, clear gw register */
+	writel(0, priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET);
+
 	return ret;
 }
 
@@ -201,6 +204,9 @@ static int mlxbf_gige_mdio_write(struct mii_bus *bus, int phy_add,
 	ret = readl_poll_timeout_atomic(priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET,
 					temp, !(temp & MLXBF_GIGE_MDIO_GW_BUSY_MASK), 100, 1000000);
 
+	/* The MDIO lock is set on read. To release it, clear gw register */
+	writel(0, priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET);
+
 	return ret;
 }
 
-- 
2.35.1