From: Krishna Reddy <vdumpa@nvidia.com>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Joerg Roedel <joerg.roedel@amd.com>,
Arnd Bergmann <arnd@arndb.de>, Hiroshi Doyu <hdoyu@nvidia.com>,
"m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
"linux@arm.linux.org.uk" <linux@arm.linux.org.uk>,
"minchan@kernel.org" <minchan@kernel.org>,
"chunsang.jeong@linaro.org" <chunsang.jeong@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"subashrp@gmail.com" <subashrp@gmail.com>,
"linaro-mm-sig@lists.linaro.org" <linaro-mm-sig@lists.linaro.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
"kyungmin.park@samsung.com" <kyungmin.park@samsung.com>,
"pullip.cho@samsung.com" <pullip.cho@samsung.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: RE: [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more precisely
Date: Wed, 19 Sep 2012 23:40:36 -0700 [thread overview]
Message-ID: <401E54CE964CD94BAE1EB4A729C7087E379FDC1F2D@HQMAIL04.nvidia.com> (raw)
In-Reply-To: <505A7DB4.4090902@wwwdotorg.org>
> > 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?
The device(H/W controller) need to access few special memory blocks(IOVA==PA)
and DRAM as well. If IOMMU is disabled, then it has to handle memory fragmentation,
which defeats the purpose of IOMMU support.
There is also a case where frame buffer memory is passed from BootLoader to Kernel and
display H/W continues to access it with IOMMU enabled. To support this, the one to one
mapping has to be setup before enabling IOMMU.
-KR
next prev parent reply other threads:[~2012-09-20 6:41 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-29 6:55 [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more precisely Hiroshi Doyu
2012-08-29 6:55 ` [RFC 1/5] ARM: dma-mapping: New dma_map_ops->iova_get_free_{total,max} functions Hiroshi Doyu
2012-08-29 6:55 ` [RFC 2/5] ARM: dma-mapping: New dma_map_ops->iova_{alloc,free}() functions Hiroshi Doyu
2012-08-29 6:55 ` [RFC 3/5] ARM: dma-mapping: New dma_map_ops->iova_alloc*_at* function Hiroshi Doyu
2012-08-29 6:55 ` [RFC 4/5] ARM: dma-mapping: New dma_map_ops->map_page*_at* function Hiroshi Doyu
2012-08-29 6:55 ` [RFC 5/5] ARM: dma-mapping: Introduce dma_map_linear_attrs() for IOVA linear map Hiroshi Doyu
2012-09-18 12:49 ` [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more precisely Joerg Roedel
2012-09-19 6:58 ` Hiroshi Doyu
2012-09-19 7:59 ` Arnd Bergmann
2012-09-19 11:41 ` Hiroshi Doyu
2012-09-19 12:50 ` Joerg Roedel
2012-09-20 1:44 ` Krishna Reddy
2012-09-20 2:21 ` Stephen Warren
2012-09-20 6:40 ` Krishna Reddy [this message]
2012-09-20 15:27 ` Stephen Warren
2012-09-21 18:16 ` Krishna Reddy
2012-09-24 9:04 ` How to specify IOMMU'able devices in DT (was: [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more precisely) Hiroshi Doyu
2012-09-24 9:28 ` James Bottomley
2012-09-24 9:44 ` Hiroshi Doyu
2012-09-24 11:14 ` Marek Szyprowski
2012-09-24 11:50 ` How to specify IOMMU'able devices in DT Hiroshi Doyu
2012-11-28 13:48 ` [PATCH 1/1] ARM: tegra: bus_notifier registers IOMMU devices(was: How to specify IOMMU'able devices in DT) Hiroshi Doyu
2012-11-28 18:07 ` Stephen Warren
2012-11-29 6:45 ` Hiroshi Doyu
2012-11-29 10:17 ` Thierry Reding
2012-11-30 4:59 ` Mark Zhang
2012-11-30 8:06 ` [PATCH 1/1] ARM: tegra: bus_notifier registers IOMMU devices Hiroshi Doyu
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