Thread (33 messages) 33 messages, 9 authors, 2016-03-31

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

From: Will Deacon <hidden>
Date: 2016-03-30 15:45:22
Also in: linux-devicetree, lkml

Hi Eric,

On Wed, Mar 30, 2016 at 05:37:27PM +0200, Eric Auger wrote:
On 01/28/2016 03:27 PM, Will Deacon wrote:
quoted
On Thu, Jan 28, 2016 at 03:17:33PM +0100, Arnd Bergmann wrote:
quoted
On Thursday 28 January 2016 12:20:58 Robin Murphy wrote:
quoted
quoted
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.
Up to now I have used the PCI smmu description as described in Suravee's
patch and this does not work anymore with 4.6-rc1 since the default
domain was introduced. So now I see 2 SMRs matching a single streamid
(in my case 256, one steming from the "platform device" side of the host
controller and one steming from the PCI device) and this causes SMCF
(stream match conflict fault). So PCIe PF does not work.
Sorry about that, it wasn't intentional. In fact, I wrote commit
cbf8277ef456 ("iommu/arm-smmu: Treat IOMMU_DOMAIN_DMA as bypass for now")
specifically to avoid this breakage, after seeing it myself with VFIO
and an S2CR-based configuration. It looks like the check just needs moving
higher up (i.e. before we initialise the SMRs).

Does that fix it for you?

Will
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