From: joro@8bytes.org ('Joerg Roedel')
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC] ARM: dma_map|unmap_sg plus iommu
Date: Fri, 29 Jul 2011 12:54:22 +0200 [thread overview]
Message-ID: <20110729105422.GB13522@8bytes.org> (raw)
In-Reply-To: <001901cc4dd8$4afb4e40$e0f1eac0$%szyprowski@samsung.com>
On Fri, Jul 29, 2011 at 12:14:25PM +0200, Marek Szyprowski wrote:
> > This sounds rather hacky. How about partitioning the address space for
> > the device and give the dma-api only a part of it. The other parts can
> > be directly mapped using the iommu-api then.
>
> Well, I'm not convinced that iommu-api should be used by the device drivers
> directly. If possible we should rather extend dma-mapping than use such hacks.
Building this into dma-api would turn it into an iommu-api. The line
between the apis are clear. The iommu-api provides direct mapping
of bus-addresses to system-addresses while the dma-api puts a memory
manager on-top which deals with bus-address allocation itself.
So if you want to map bus-addresses directly the iommu-api is the way to
go. This is in no way a hack.
Regards,
Joerg
WARNING: multiple messages have this Message-ID (diff)
From: 'Joerg Roedel' <joro@8bytes.org>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: "'Ramirez Luna, Omar'" <omar.ramirez@ti.com>,
linux-arm-kernel@lists.infradead.org,
linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org,
'Kyungmin Park' <kyungmin.park@samsung.com>,
'Russell King - ARM Linux' <linux@arm.linux.org.uk>,
'Arnd Bergmann' <arnd@arndb.de>,
'Ohad Ben-Cohen' <ohad@wizery.com>
Subject: Re: [RFC] ARM: dma_map|unmap_sg plus iommu
Date: Fri, 29 Jul 2011 12:54:22 +0200 [thread overview]
Message-ID: <20110729105422.GB13522@8bytes.org> (raw)
In-Reply-To: <001901cc4dd8$4afb4e40$e0f1eac0$%szyprowski@samsung.com>
On Fri, Jul 29, 2011 at 12:14:25PM +0200, Marek Szyprowski wrote:
> > This sounds rather hacky. How about partitioning the address space for
> > the device and give the dma-api only a part of it. The other parts can
> > be directly mapped using the iommu-api then.
>
> Well, I'm not convinced that iommu-api should be used by the device drivers
> directly. If possible we should rather extend dma-mapping than use such hacks.
Building this into dma-api would turn it into an iommu-api. The line
between the apis are clear. The iommu-api provides direct mapping
of bus-addresses to system-addresses while the dma-api puts a memory
manager on-top which deals with bus-address allocation itself.
So if you want to map bus-addresses directly the iommu-api is the way to
go. This is in no way a hack.
Regards,
Joerg
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next prev parent reply other threads:[~2011-07-29 10:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-28 21:09 [RFC] ARM: dma_map|unmap_sg plus iommu Ramirez Luna, Omar
2011-07-28 21:09 ` Ramirez Luna, Omar
2011-07-29 7:50 ` Marek Szyprowski
2011-07-29 7:50 ` Marek Szyprowski
2011-07-29 9:35 ` 'Joerg Roedel'
2011-07-29 9:35 ` 'Joerg Roedel'
2011-07-29 10:14 ` Marek Szyprowski
2011-07-29 10:14 ` Marek Szyprowski
2011-07-29 10:54 ` 'Joerg Roedel' [this message]
2011-07-29 10:54 ` 'Joerg Roedel'
2011-07-29 14:24 ` Marek Szyprowski
2011-07-29 14:24 ` Marek Szyprowski
2011-08-01 0:57 ` KyongHo Cho
2011-08-01 0:57 ` KyongHo Cho
2011-08-08 15:21 ` Ramirez Luna, Omar
2011-08-08 15:21 ` Ramirez Luna, Omar
2011-08-08 15:29 ` Russell King - ARM Linux
2011-08-08 15:29 ` Russell King - ARM Linux
2011-08-09 7:04 ` Marek Szyprowski
2011-08-09 7:04 ` Marek Szyprowski
2011-08-08 15:04 ` Ramirez Luna, Omar
2011-08-08 15:04 ` Ramirez Luna, Omar
2011-08-09 6:51 ` Marek Szyprowski
2011-08-09 6:51 ` Marek Szyprowski
2011-08-13 14:39 ` Ramirez Luna, Omar
2011-08-13 14:39 ` Ramirez Luna, Omar
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