Re: [PATCH net v1] net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data

Jon Hunter
2024-12-04T17:03:25Z

On 03/12/2024 03:16, Furong Xu wrote:
> On Mon, 2 Dec 2024 18:34:25 -0800, Jakub Kicinski <kuba@kernel.org> wrote:
>
>> On Tue, 3 Dec 2024 10:03:31 +0800 Furong Xu wrote:
>>> I requested Jon to provide more info about "Tx DMA map failed" in previous
>>> reply, and he does not respond yet.
>>
>> What does it mean to provide "more info" about a print statement from
>> the driver? Is there a Kconfig which he needs to set to get more info?
>> Perhaps you should provide a debug patch he can apply on his tree, that
>> will print info about (1) which buffer mapping failed (head or frags);
>> (2) what the physical address was of the buffer that couldn't be mapped.
>
> A debug patch to print info about buffer makes no sense here.
> Both Tegra186 Jetson TX2(tegra186-p2771-0000) and Tegra194 Jetson AGX Xavier
> (tegra194-p2972-0000) enable IOMMU/SMMU for stmmac in its device-tree node,
> buffer info should be investigated with detailed IOMMU/SMMU debug info from
> drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c together.
>
> I am not an expert in IOMMU, so I cannot help more.
>
> Without the help from Jon, our only choice is revert as you said.

Sorry Thierry and I were digging into this offline but yes I can provide
any more info that is needed.

Jon

--
nvpublic