From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 2/7] ARM: Samsung: update/rewrite Samsung SYSMMU (IOMMU) driver
Date: Tue, 19 Apr 2011 17:37:30 +0200
Message-ID: <201104191737.30916.arnd@arndb.de>
References: <1303118804-5575-1-git-send-email-m.szyprowski@samsung.com> <000001cbfe9a$8e64cae0$ab2e60a0$%szyprowski@samsung.com> <20110419150018.GV2192@amd.com>
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To: "Roedel, Joerg" <Joerg.Roedel@amd.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>, "linux-samsung-soc@vger.kernel.org" <linux-samsung-soc@vger.kernel.org>, 'Kyungmin Park' <kyungmin.park@samsung.com>, 'Kukjin Kim' <kgene.kim@samsung.com>, 'Sylwester Nawrocki' <s.nawrocki@samsung.com>, 'Andrzej Pietrasiewicz' <andrzej.p@samsung.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
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On Tuesday 19 April 2011, Roedel, Joerg wrote:
> > Getting back to our video codec - it has 2 IOMMU controllers. The codec
> > hardware is able to address only 256MiB of space. Do you have an idea how
> > this can be handled with dma-mapping API? The only idea that comes to my
> > mind is to provide a second, fake 'struct device' and use it for allocations
> > for the second IOMMU controller.
> 
> The GPU IOMMUs can probably be handled in the GPU driver if they are
> that different. Recent PCIe GPUs on x86 have their own IOMMUs too which
> are very device specific and are handled in the device driver.

I tend to disagree with this one, and would suggest that the GPUs should
actually provide their own iommu_ops, even if they are the only users
of these.

However, this is a minor point that we don't need to worry about today.

	Arnd

From mboxrd@z Thu Jan  1 00:00:00 1970
From: arnd@arndb.de (Arnd Bergmann)
Date: Tue, 19 Apr 2011 17:37:30 +0200
Subject: [PATCH 2/7] ARM: Samsung: update/rewrite Samsung SYSMMU (IOMMU)
	driver
In-Reply-To: <20110419150018.GV2192@amd.com>
References: <1303118804-5575-1-git-send-email-m.szyprowski@samsung.com>
	<000001cbfe9a$8e64cae0$ab2e60a0$%szyprowski@samsung.com>
	<20110419150018.GV2192@amd.com>
Message-ID: <201104191737.30916.arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Tuesday 19 April 2011, Roedel, Joerg wrote:
> > Getting back to our video codec - it has 2 IOMMU controllers. The codec
> > hardware is able to address only 256MiB of space. Do you have an idea how
> > this can be handled with dma-mapping API? The only idea that comes to my
> > mind is to provide a second, fake 'struct device' and use it for allocations
> > for the second IOMMU controller.
> 
> The GPU IOMMUs can probably be handled in the GPU driver if they are
> that different. Recent PCIe GPUs on x86 have their own IOMMUs too which
> are very device specific and are handled in the device driver.

I tend to disagree with this one, and would suggest that the GPUs should
actually provide their own iommu_ops, even if they are the only users
of these.

However, this is a minor point that we don't need to worry about today.

	Arnd