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Subject: Re: [PATCH v4 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe_device()
From:   Dmitry Osipenko <digetx@gmail.com>
To:     Nicolin Chen <nicoleotsuka@gmail.com>, thierry.reding@gmail.com,
        joro@8bytes.org, Maxime Ripard <maxime@cerno.tech>
Cc:     vdumpa@nvidia.com, jonathanh@nvidia.com,
        linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
References: <20201002060807.32138-1-nicoleotsuka@gmail.com>
 <20201002060807.32138-3-nicoleotsuka@gmail.com>
 <99d322d0-efb5-8a34-ee83-b907b785ced3@gmail.com>
Message-ID: <3ecfe9ae-fa32-8384-c912-4e17ff5fede7@gmail.com>
Date:   Fri, 2 Oct 2020 19:00:38 +0300
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02.10.2020 18:23, Dmitry Osipenko пишет:
> 02.10.2020 09:08, Nicolin Chen пишет:
>> Then when a client gets probed, of_iommu_configure() in
>> iommu core will search DTB for swgroup ID and call ->of_xlate()
>> to prepare an fwspec, similar to tegra_smmu_probe_device() and
>> tegra_smmu_configure(). Then it'll call tegra_smmu_probe_device()
>> again, and this time we shall return smmu->iommu pointer properly.
> 
> I don't quite see where IOMMU core calls of_xlate().
> 
> Have tried to at least boot-test this patch?
> 

I don't see how it ever could work because of_xlate() is only invoked from:

fsl_mc_dma_configure()->of_dma_configure_id()->of_iommu_configure()

Looks like the tegra_smmu_configure() is still needed.

I don't know how sun50i driver could work to be honest. Seems IOMMU is
broken on sun50i, but maybe I'm missing something.

I added Maxime Ripard to this thread, who is the author of the
sun50i-iommu driver.