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Message-ID: <471F2D72.1060501@garzik.org>
Date: Wed, 24 Oct 2007 07:33:06 -0400
From: Jeff Garzik <jeff@...zik.org>
To: FUJITA Tomonori <tomof@....org>
CC: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
linux-scsi@...r.kernel.org, James.Bottomley@...elEye.com,
jens.axboe@...cle.com, greg@...ah.com,
fujita.tomonori@....ntt.co.jp
Subject: Re: [PATCH -mm 01/11] add device_dma_parameters structure
FUJITA Tomonori wrote:
> iommu code merges scatter/gather segments without considering a low
> level driver's restrictions. The problem is that iommu code can't
> access to the limitations because they are in request_queue.
>
> This patch adds a new structure, device_dma_parameters, including dma
> information. A pointer to device_dma_parameters is added to struct
> device.
>
> - there are only max_segment_size and segment_boundary_mask there but
> we'll move more dma stuff in struct device (like dma_mask) to struct
> device_dma_parameters later. segment_boundary_mask is not supported
> yet.
>
> - new accessors for the dma parameters are added. So we can easily
> change where to place struct device_dma_parameters in the future.
>
> - dma_get_max_seg_size returns 64K if dma_parms in struct device isn't
> set up properly. 64K is the default max_segment_size in the block
> layer.
>
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
> ---
> include/linux/device.h | 11 +++++++++++
> include/linux/dma-mapping.h | 15 +++++++++++++++
> 2 files changed, 26 insertions(+), 0 deletions(-)
ACK
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