[PATCH] net: stmmac: dwc-qos: Disable split header for Tegra194

[PATCH] net: stmmac: dwc-qos: Disable split header for Tegra194

[Jon Hunter]

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

Re: [PATCH] net: stmmac: dwc-qos: Disable split header for Tegra194

[Jakub Kicinski]

On Wed, 6 Jul 2022 09:39:13 +0100 Jon Hunter wrote:
> 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>

Fixes: 67afd6d1cfdf ("net: stmmac: Add Split Header support and enable it in XGMAC cores")

correct?

Re: [PATCH] net: stmmac: dwc-qos: Disable split header for Tegra194

[Jon Hunter]

On 07/07/2022 03:11, Jakub Kicinski wrote:
> On Wed, 6 Jul 2022 09:39:13 +0100 Jon Hunter wrote:
>> 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>
> 
> Fixes: 67afd6d1cfdf ("net: stmmac: Add Split Header support and enable it in XGMAC cores")
> 
> correct?


Yes that is correct. I forgot to add. Let me know if you want me to send 
a V2.

Thanks
Jon

-- 
nvpublic

Re: [PATCH] net: stmmac: dwc-qos: Disable split header for Tegra194

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 6 Jul 2022 09:39:13 +0100 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - net: stmmac: dwc-qos: Disable split header for Tegra194
    https://git.kernel.org/netdev/net/c/029c1c2059e9

You are awesome, thank you!
-- 
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