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From:   Jon Hunter <jonathanh@nvidia.com>
To:     Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        "Jakub Kicinski" <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-tegra@vger.kernel.org>, Jon Hunter <jonathanh@nvidia.com>
Subject: [PATCH] net: stmmac: dwc-qos: Disable split header for Tegra194
Date:   Wed, 6 Jul 2022 09:39:13 +0100
Message-ID: <20220706083913.13750-1-jonathanh@nvidia.com>
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There is a long-standing issue with the Synopsys DWC Ethernet driver
for Tegra194 where random system crashes have been observed [0]. The
problem occurs when the split header feature is enabled in the stmmac
driver. In the bad case, a larger than expected buffer length is
received and causes the calculation of the total buffer length to
overflow. This results in a very large buffer length that causes the
kernel to crash. Why this larger buffer length is received is not clear,
however, the feedback from the NVIDIA design team is that the split
header feature is not supported for Tegra194. Therefore, disable split
header support for Tegra194 to prevent these random crashes from
occurring.

[0] https://lore.kernel.org/linux-tegra/b0b17697-f23e-8fa5-3757-604a86f3a095@nvidia.com/

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c
index bc91fd867dcd..358fc26f8d1f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c
@@ -361,6 +361,7 @@ static int tegra_eqos_probe(struct platform_device *pdev,
 	data->fix_mac_speed = tegra_eqos_fix_speed;
 	data->init = tegra_eqos_init;
 	data->bsp_priv = eqos;
+	data->sph_disable = 1;
 
 	err = tegra_eqos_init(pdev, eqos);
 	if (err < 0)
-- 
2.25.1