From: Jose Abreu <joabreu@synopsys.com>
Date: Jul/27/2019, 16:56:37 (UTC+00:00)

> From: Jon Hunter <jonathanh@nvidia.com>
> Date: Jul/26/2019, 15:11:00 (UTC+00:00)
> 
> > 
> > On 25/07/2019 16:12, Jose Abreu wrote:
> > > From: Jon Hunter <jonathanh@nvidia.com>
> > > Date: Jul/25/2019, 15:25:59 (UTC+00:00)
> > > 
> > >>
> > >> On 25/07/2019 14:26, Jose Abreu wrote:
> > >>
> > >> ...
> > >>
> > >>> Well, I wasn't expecting that :/
> > >>>
> > >>> Per documentation of barriers I think we should set descriptor fields 
> > >>> and then barrier and finally ownership to HW so that remaining fields 
> > >>> are coherent before owner is set.
> > >>>
> > >>> Anyway, can you also add a dma_rmb() after the call to 
> > >>> stmmac_rx_status() ?
> > >>
> > >> Yes. I removed the debug print added the barrier, but that did not help.
> > > 
> > > So, I was finally able to setup NFS using your replicated setup and I 
> > > can't see the issue :(
> > > 
> > > The only difference I have from yours is that I'm using TCP in NFS 
> > > whilst you (I believe from the logs), use UDP.
> > 
> > So I tried TCP by setting the kernel boot params to 'nfsvers=3' and
> > 'proto=tcp' and this does appear to be more stable, but not 100% stable.
> > It still appears to fail in the same place about 50% of the time.
> > 
> > > You do have flow control active right ? And your HW FIFO size is >= 4k ?
> > 
> > How can I verify if flow control is active?
> 
> You can check it by dumping register MTL_RxQ_Operation_Mode (0xd30).
> 
> Can you also add IOMMU debug in file "drivers/iommu/iommu.c" ?

And, please try attached debug patch.

---
Thanks,
Jose Miguel Abreu