Re: [PATCH 11/13] dtb: amd: Add PCIe SMMU device tree node

From: Will Deacon
Date: Thu Jan 28 2016 - 09:28:07 EST

On Thu, Jan 28, 2016 at 03:17:33PM +0100, Arnd Bergmann wrote:
> On Thursday 28 January 2016 12:20:58 Robin Murphy wrote:
> > >
> > > Will, Robin, thoughts?
> >
> > Any IDs specified here would only apply to DMA by the "platform device"
> > side of the host controller itself (as would an equivalent "iommus"
> > property on pcie0 once I finish the SMMUv2 generic binding support I'm
> > working on). In terms of PCI devices, the "mmu-masters" property is
> > overloaded such that only its existence matters, to identify that there
> > _is_ a relationship between the SMMU and the PCI bus(es) behind that
> > host controller.
> I wasn't aware that this was actually still specified. I had hoped
> we were getting rid of mmu-masters before anyone actually started
> using it, but now I see it in ns2.dtsi and fsl-ls2080a.dtsi.
> Does anyone know what happened to the plan to use the iommu DT binding
> for the ARM SMMU instead? Do we now have to support both ways indefinitely?

We always did -- Seattle used the mmu-masters binding before the generic
binding even existed. Robin has been working on patches to get of_xlate
up and running, but it got held up by Laurent's series which didn't end
up going anywhere.