-----Original Message-----
From: Jon Hunter <jonathanh@nvidia.com>
Sent: 2021年3月30日 20:51
To: Joakim Zhang <redacted>
Cc: netdev@vger.kernel.org; Linux Kernel Mailing List
[off-list ref]; linux-tegra [off-list ref];
Jakub Kicinski [off-list ref]
Subject: Re: Regression v5.12-rc3: net: stmmac: re-init rx buffers when mac
resume back



On 25/03/2021 08:12, Joakim Zhang wrote:

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You mean one of your boards? Does other boards with STMMAC can
work

fine?

We have two devices with the STMMAC and one works OK and the other

fails.

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They are different generation of device and so there could be some
architectural differences which is causing this to only be seen on one

device.

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It's really strange, but I also don't know what architectural
differences could

affect this. Sorry.

I realised that for the board which fails after this change is made, it has the
IOMMU enabled. The other board does not at the moment (although work is in
progress to enable). If I add 'iommu.passthrough=1' to cmdline for the failing
board, then it works again. So in my case, the problem is linked to the IOMMU
being enabled.

Does you platform enable the IOMMU?

Hi Jon,

There is no IOMMU hardware available on our boards. But why IOMMU would affect it during suspend/resume, and no problem in normal mode?

Best Regards,
Joakim Zhang

Thanks
Jon

--
nvpublic