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Subject: Re: [PATCH v3 0/6] Prerequisites for NXP LS104xA SMMU enablement
To:     Christoph Hellwig <hch@infradead.org>,
        David Miller <davem@davemloft.net>
Cc:     madalin.bucur@nxp.com, netdev@vger.kernel.org, roy.pledge@nxp.com,
        linux-kernel@vger.kernel.org, leoyang.li@nxp.com,
        Joakim.Tjernlund@infinera.com, iommu@lists.linux-foundation.org,
        camelia.groza@nxp.com, linuxppc-dev@lists.ozlabs.org,
        linux-arm-kernel@lists.infradead.org
References: <20190530141951.6704-1-laurentiu.tudor@nxp.com>
 <20190530.150844.1826796344374758568.davem@davemloft.net>
 <20190531163350.GB8708@infradead.org>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <37406608-df48-c7a0-6975-4b4ad408ba36@arm.com>
Date:   Fri, 31 May 2019 18:03:30 +0100
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On 31/05/2019 17:33, Christoph Hellwig wrote:
> On Thu, May 30, 2019 at 03:08:44PM -0700, David Miller wrote:
>> From: laurentiu.tudor@nxp.com
>> Date: Thu, 30 May 2019 17:19:45 +0300
>>
>>> Depends on this pull request:
>>>
>>>   http://lists.infradead.org/pipermail/linux-arm-kernel/2019-May/653554.html
>>
>> I'm not sure how you want me to handle this.
> 
> The thing needs to be completely redone as it abuses parts of the
> iommu API in a completely unacceptable way.

`git grep iommu_iova_to_phys drivers/{crypto,gpu,net}`

:(

I guess one alternative is for the offending drivers to maintain their 
own lookup tables of mapped DMA addresses - I think at least some of 
these things allow storing some kind of token in a descriptor, which 
even if it's not big enough for a virtual address might be sufficient 
for an index.

Robin.