Re: [PATCH -mm 01/11] add device_dma_parameters structure

Jeff Garzik
2007-10-24T11:33:20Z

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@lab.ntt.co.jp>
> ---
> include/linux/device.h | 11 +++++++++++
> include/linux/dma-mapping.h | 15 +++++++++++++++
> 2 files changed, 26 insertions(+), 0 deletions(-)

ACK