# RE: Regression v5.12-rc3: net: stmmac: re-init rx buffers when mac resume back

- From: Joakim Zhang \<hidden\>
- Date: 2021-03-31 11:11:20 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/03/6322578
- Thread: https://ratatoskr.run/netdev/2021/03/6313636/t.md

```text

> -----Original Message-----
> From: Joakim Zhang <redacted>
> Sent: 2021年3月31日 15:44
> To: Jon Hunter <jonathanh@nvidia.com>
> Cc: <redacted>; Linux Kernel Mailing List
> [ref]; linux-tegra [ref];
> Jakub Kicinski [ref]
> Subject: RE: Regression v5.12-rc3: net: stmmac: re-init rx buffers when mac
> resume back
> 
> 
> > -----Original Message-----
> > From: Jon Hunter <jonathanh@nvidia.com>
> > Sent: 2021年3月30日 20:51
> > To: Joakim Zhang <redacted>
> > Cc: <redacted>; Linux Kernel Mailing List
> > [ref]; linux-tegra
> > [ref]; Jakub Kicinski [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:
> >
> > ...
> >
> > >>>>> 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?

One more add, I saw drivers/iommu/tegra-gart.c(not sure if is this) support suspend/resume, is it possible iommu resume back after stmmac?

Best Regards,
Joakim Zhang
> Best Regards,
> Joakim Zhang
> > Thanks
> > Jon
> >
> > --
> > nvpublic
```