Re: [PATCH V3] pci: exynos: split into two parts such as Synopsys part and Exynos part

From: Arnd Bergmann
Date: Thu Sep 26 2013 - 05:52:03 EST

On Thursday 26 September 2013, Kishon Vijay Abraham I wrote:
> On Wednesday 25 September 2013 02:53 AM, Arnd Bergmann wrote:
> > On Monday 23 September 2013, Kishon Vijay Abraham I wrote:
> >> Btw if we hadn't programmed inbound translation table, the address will go
> >> untranslated (according to the data book). I guess that's how it was working
> >> for Jingoo Han.
> >>
> >> **
> >> 3.10.4
> >> Inbound iATU Operation
> >>
> >> When there is no match, then the address is untranslated
> >> **
> >>
> >
> > Well, that should work just as well, since you have a 1:1 translation anyway.
> > Do you get the same error without the translation?
> Yes. I get the same non-fatal error interrupt in RC.

Ok, then I guess the translation is actually not at fault here but something
else. I would recommend looking at the IOMMU as the potential culprit. Maybe
having it disabled means that no DMA is going through, rather than all DMA
going through untranslated. Another possibility is that the IOMMU is set up
so that when disabled, it maps DMA address 0 to the start of RAM, rather
than identity mapping DMA address 0x80000000 there. If that's the case,
you either have to use the IOMMU, or set up the mapping in the root
complex to revert it.

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