Forums - Disable SMMU

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Disable SMMU
vinuchandran
Join Date: 1 Dec 20
Posts: 13
Posted: Sun, 2021-02-07 22:58

Hi,

We have a custom DMA PCIe card. When doing datatransfer, some context fault errors are coming with the RB5.

But the card works fine in other boards/platforms like Nvidia TX2, iMX8, x86_64 etc.

We suspect if the SMMU is at fault. I tried disabling some kernel configs, but the kernel build itself is failing. 
Is there a way to disable SMMU for the RB5 board?

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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Mon, 2021-02-08 16:01

Let me check our hardware engineer. 

Thanks

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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Tue, 2021-02-09 13:38

Hi vinuchandran

Can you provide us your PCie card connection to board or schematic?

Thanks

Kevin

 

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vinuchandran
Join Date: 1 Dec 20
Posts: 13
Posted: Thu, 2021-02-11 00:38

Hi Kevin,

The following are the connections.

HS2-19 (GPIO 85)  PCIE2_RST_N
HS2-21 (GPIO 86) PCIE2_CLK_REQ_N
HS2-23 (GPIO 87) PCIE2_WAKE_N  (not connected)
HS3-14, HS3-16     PCIE2_REFCLK_M, PCIE2_REFCLK_P
HS3-18, HS3-20     PCIE2_RX0_M, PCIE2_RX0_P
HS3-22, HS3-24     PCIE2_RX1_M, PCIE2_RX1_P
HS3-26, HS3-28     PCIE2_TX0_M, PCIE2_TX0_P
HS3-30, HS3-32     PCIE2_TX1_M, PCIE2_TX1_P

CLK_REQ_N is pull-down 
We don't use Wake.
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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Mon, 2021-02-15 10:31

Thank your information, I will provide the connection information to system /hardware enginners

I will let you know result soon

Thanks

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vinuchandran
Join Date: 1 Dec 20
Posts: 13
Posted: Sun, 2021-02-21 21:19

Hi Kevin,

Any updates on this?

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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Mon, 2021-02-22 09:43

Hi vinuchandran

I am waiting hardware engineer to confirm PCIE connection on board.

You tried to build debugging kernel? you have kernel source?

If you provide me the debugging pacth,  I can build kernel for you.

Thanks

Kevin

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vinuchandran
Join Date: 1 Dec 20
Posts: 13
Posted: Wed, 2021-02-24 07:37

Hi Kevin.

I have disabled IOMMU_SUPPORT on the Kernel config.
But the kernel build has failed.

I couldn't find any documented steps to disable the SMMU.

Can you provide the necessary procedure?

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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Wed, 2021-02-24 09:34

I will try to build it.

Thanks

Kevin

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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Mon, 2021-03-08 11:41

Where did you enable IOMMU_SUPPORT?

I checked the kernel configue file kona-perf_deconfig, and haven't found IOMMU_SUPPORT set or not set definition.

Let me know where you set IOMMU_SUPPORT.

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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Mon, 2021-03-08 11:41

Where did you enable IOMMU_SUPPORT?

I checked the kernel configue file kona-perf_deconfig, and haven't found IOMMU_SUPPORT set or not set definition.

Let me know where you set IOMMU_SUPPORT.

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vinuchandran
Join Date: 1 Dec 20
Posts: 13
Posted: Thu, 2021-03-18 23:04

CONFIG_IOMMU_SUPPORT is the config flag.

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kevin.dai
Join Date: 21 Oct 20
Posts: 137
Posted: Mon, 2021-03-22 11:41

I added

CONFIG_IOMMU_SUPPORT=y

in kona-perf_debugcinfig, the kernel could not be built. I wonder if RB5 platform support IOMMU? let me check someone about IOMMU on RB5

Thanks

 

 

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