From mboxrd@z Thu Jan  1 00:00:00 1970
From: swarren@wwwdotorg.org (Stephen Warren)
Date: Wed, 19 Sep 2012 20:21:40 -0600
Subject: [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more
 precisely
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To: linux-arm-kernel@lists.infradead.org
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On 09/19/2012 07:44 PM, Krishna Reddy wrote:
>> When a device driver would only use the IOMMU-API and needs small DMA-
>> able areas it has to re-implement something like the DMA-API (basically an
>> address allocator) for that. So I don't see a reason why both can't be used in a
>> device driver.
> 
> On Tegra, the following use cases need specific IOVA mapping.
> 1. Few MMIO blocks need IOVA=PA mapping setup.

In that case, why would we enable the IOMMU for that one device; IOMMU
disabled means VA==PA, right? Perhaps isolation of the device so it can
only access certain PA ranges for security?