From mboxrd@z Thu Jan  1 00:00:00 1970
From: KyongHo Cho <pullip.cho@samsung.com>
Subject: Re: [Linaro-mm-sig] [PATCH 3/8] ARM: dma-mapping: use asm-generic/dma-mapping-common.h
Date: Mon, 20 Jun 2011 23:33:00 +0900
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To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, Kyungmin Park <kyungmin.park@samsung.com>, Russell King - ARM Linux <linux@arm.linux.org.uk>, Joerg Roedel <joro@8bytes.org>, Arnd Bergmann <arnd@arndb.de>

Hi.

Great job.

On Mon, Jun 20, 2011 at 4:50 PM, Marek Szyprowski
<m.szyprowski@samsung.com> wrote:
> +static inline void set_dma_ops(struct device *dev, struct dma_map_op=
s *ops)
> +{
> + =A0 =A0 =A0 dev->archdata.dma_ops =3D ops;
> +}
> +

Who calls set_dma_ops()?
In the mach. initialization part?
What if a device driver does not want to use arch's dma_map_ops
when machine init procedure set a dma_map_ops?
Even though, may arch defiens their dma_map_ops in archdata of device s=
tructure,
I think it is not a good idea that is device structure contains a
pointer to dma_map_ops
that may not be common to all devices in a board.

I also think that it is better to attach and to detach dma_map_ops dyna=
mically.
Moreover, a mapping is not permanent in our Exynos platform
because a System MMU may be turned off while runtime.

DMA API must come with IOMMU API to initialize IOMMU in runtime.

Regards,
Cho KyongHo.