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Subject: Re: [PATCH 2/2] iommu: add Unisoc iommu basic driver
To:     Joerg Roedel <joro@8bytes.org>
Cc:     Chunyan Zhang <zhang.lyra@gmail.com>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Chunyan Zhang <chunyan.zhang@unisoc.com>,
        Sheng Xu <sheng.xu@unisoc.com>,
        iommu@lists.linux-foundation.org, Rob Herring <robh+dt@kernel.org>,
        Baolin Wang <baolin.wang7@gmail.com>,
        Orson Zhai <orsonzhai@gmail.com>
References: <20210202073258.559443-3-zhang.lyra@gmail.com>
 <20210202104257.736836-1-zhang.lyra@gmail.com>
 <20210202140101.GA32671@8bytes.org>
 <992fad43-c457-d809-3bd7-7fd5b6e8fa22@arm.com>
 <20210202144126.GC32671@8bytes.org>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <5e766b74-ab51-8c47-66c1-ca65bc5743cd@arm.com>
Date:   Tue, 2 Feb 2021 18:02:15 +0000
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On 2021-02-02 14:41, Joerg Roedel wrote:
> On Tue, Feb 02, 2021 at 02:34:34PM +0000, Robin Murphy wrote:
>> Nope, I believe if Arm Ltd. had any involvement in this I'd know about it :)
> 
> Okay, got confused by thinking of ARM as the CPU architecture, not the
> company :)
> But given the intel/ and amd/ subdirectories refer to company names as
> well, the same is true for arm/.

Right, trying to group IOMMU drivers by supposed CPU architecture is 
already a demonstrable non-starter; does intel-iommu count as x86, or 
IA-64, or do you want two copies? :P

I somehow doubt anyone would license one of Arm's SMMUs to go in a 
RISC-V/MIPS/etc. based SoC, but in principle, they *could*. In fact it's 
precisely cases like this one - where silicon vendors come up with their 
own little scatter-gather unit to go with their own display controller 
etc. - that I imagine are most likely to get reused if the vendor 
decides to experiment with different CPUs to reach new market segments.

Robin.