linux-kernel - Re: [PATCH] iommu/of: Fix of_iommu

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Date:   Fri, 4 Aug 2017 13:57:00 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Robin Murphy <robin.murphy@....com>, joro@...tes.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/of: Fix of_iommu_configure() for disabled IOMMUs



On 04/08/17 12:16, Robin Murphy wrote:
> Sudeep reports that the logic is slightly broken when a PCI iommu-map
> entry targets an IOMMU marked as disabled in DT, since of_pci_map_rid()
> succeeds in following a phandle, and of_iommu_xlate() doesn't return an
> error value, but we miss checking whether ops was actually non-NULL.
> Whilst this could be solved with a point fix in of_pci_iommu_init(), it
> suggests that all the juggling of ERR_PTR values through the ops pointer
> is proving rather too complicated for its own good, so let's instead
> simplify the whole flow (with a side-effect of eliminating the cause of
> the bug).
> 
> The fact that we now rely on iommu_fwspec means that we no longer need
> to pass around an iommu_ops pointer at all - we can simply propagate a
> regular int return value until we know whether we have a viable IOMMU,
> then retrieve the ops from the fwspec if and when we actually need them.
> This makes everything a bit more uniform and certainly easier to follow.
> 
> Reported-by: Sudeep Holla <sudeep.holla@....com>

Tested-by: Sudeep Holla <sudeep.holla@....com>

-- 
Regards,
Sudeep