Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
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>
 <3ecfe9ae-fa32-8384-c912-4e17ff5fede7@gmail.com>
 <6018e1c5-9ddd-3e37-1d6b-3feb969a7474@gmail.com>
Message-ID: <1516a3e1-452f-6b40-ab34-4820c502c1c3@gmail.com>
Date:   Fri, 2 Oct 2020 19:50:43 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <6018e1c5-9ddd-3e37-1d6b-3feb969a7474@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk

02.10.2020 19:37, Dmitry Osipenko пишет:
> 02.10.2020 19:00, Dmitry Osipenko пишет:
>> 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.
>>
> 
> Actually, I now see that the other IOMMU drivers (qcom, exynos, etc) do
> the same. So obviously I'm missing something and it should work..
> 

Okay, somehow I was oblivious to that of_dma_configure() invokes
of_dma_configure_id(). Should be good :)