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Date:   Wed, 29 Nov 2023 20:46:03 -0400
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     Joerg Roedel <joro@8bytes.org>, Christoph Hellwig <hch@lst.de>,
        Vineet Gupta <vgupta@kernel.org>,
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        Catalin Marinas <catalin.marinas@arm.com>,
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        Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Paul Walmsley <paul.walmsley@sifive.com>,
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        Albert Ou <aou@eecs.berkeley.edu>,
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        Sudeep Holla <sudeep.holla@arm.com>,
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        Haiyang Zhang <haiyangz@microsoft.com>,
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Subject: Re: [PATCH 2/7] OF: Simplify DMA range calculations
Message-ID: <20231130004603.GB1394392@ziepe.ca>
References: <cover.1701268753.git.robin.murphy@arm.com>
 <73becf4a75f15662b2dda5fba7cfeacdf3d866f8.1701268753.git.robin.murphy@arm.com>
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On Wed, Nov 29, 2023 at 05:42:59PM +0000, Robin Murphy wrote:
> Juggling start, end, and size values for a range is somewhat redundant
> and a little hard to follow. Consolidate down to just using inclusive
> start and end, which saves us worrying about size overflows for full
> 64-bit ranges (note that passing a potentially-overflowed value through
> to arch_setup_dma_ops() is benign for all current implementations, and
> this is working towards removing that anyway).

In iommu code I've been trying to use consistent language with other
parts of the kernel like interval tree and maple tree:

 * In this file the term 'last' indicates an inclusive and closed interval, eg
 * [0,0] refers to a single PFN. 'end' means an open range, eg [0,0) refers to
 * no PFNs.

Here I think you've swapped end to mean last?

Regardless the change looks correct

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason