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 11:35:55 +0200 [thread overview]
Message-ID: <20110729093555.GA13522@8bytes.org> (raw)
In-Reply-To: <000301cc4dc4$31b53630$951fa290$%szyprowski@samsung.com>
On Fri, Jul 29, 2011 at 09:50:32AM +0200, Marek Szyprowski wrote:
> On Thursday, July 28, 2011 11:10 PM Ramirez Luna, Omar wrote:
> > 2. tidspbridge driver sometimes needs to map a physical address into a
> > fixed virtual address (i.e. the start of a firmware section is expected to
> > be at dsp va 0x20000000), there is no straight forward way to do this with
> > the dma api given that it only expects to receive a cpu_addr, a sg or a
> > page, by adding iov_address I could pass phys and iov addresses in a sg
> > and overcome this limitation, but, these addresses belong to:
>
> We also encountered the problem of fixed firmware address. We addressed is by
> setting io address space start to this address and letting device driver to
> rely on the fact that the first call to dma_alloc() will match this address.
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.
Regards,
Joerg
1
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next prev parent reply other threads:[~2011-07-29 9:35 UTC|newest]
Thread overview: 13+ 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
2011-07-29 7:50 ` Marek Szyprowski
2011-07-29 9:35 ` 'Joerg Roedel' [this message]
2011-07-29 10:14 ` Marek Szyprowski
2011-07-29 10:54 ` 'Joerg Roedel'
2011-07-29 14:24 ` Marek Szyprowski
2011-08-01 0:57 ` KyongHo Cho
2011-08-08 15:21 ` Ramirez Luna, Omar
2011-08-08 15:29 ` Russell King - ARM Linux
2011-08-09 7:04 ` Marek Szyprowski
2011-08-08 15:04 ` Ramirez Luna, Omar
2011-08-09 6:51 ` Marek Szyprowski
2011-08-13 14:39 ` Ramirez Luna, Omar
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