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Subject: Re: Regression v5.12-rc3: net: stmmac: re-init rx buffers when mac
 resume back
To:     Joakim Zhang <qiangqing.zhang@nxp.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
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From:   Jon Hunter <jonathanh@nvidia.com>
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Date:   Wed, 31 Mar 2021 12:11:42 +0100
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On 31/03/2021 08:43, Joakim Zhang wrote:

...

>>>>>>> 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.
>>>>>> 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.
>>>>> 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?


I am not sure either and I don't see anything obvious.

Guiseppe, Alexandre, Jose, do you see anything that is wrong with
Joakim's change 9c63faaa931e? This is completely breaking resume from
suspend on one of our boards and I would like to get your inputs?

Thanks
Jon

-- 
nvpublic